feasibility report heating of refrigerated lpg with … · 11/04/2017 · feasibility report 1....

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Ilias Seferoglou | OCTOBER 2017

FEASIBILITY REPORT

HEATING OF REFRIGERATED LPG WITH SOLAR ENERGY

Heating of the Refrigerated LPG with Solar Energy Ilias Seferoglou

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Contents

1. INTRODUCTION .....................................................................................................................................3

2. DESCRIPTION OF THE INDUSTRIAL OPERATION....................................................................................3

2.1 CONDITIONS OF THE LPG AT THE VLGC ..............................................................................................4

2.2 STORAGE OF THE LPG AT THE TERMINAL ...........................................................................................4

2.3 DELIVERY OF THE LPG .........................................................................................................................4

3. SCOPE OF THE INVESTIGATION .............................................................................................................5

4. HEATING REQUIREMENTS .....................................................................................................................5

5. SOLAR HEATING ....................................................................................................................................7

6. SOLAR THERMAL TECHNOLOGIES/SOLAR COLLECTORS .......................................................................8

7. CONCLUSION ON THE SOLAR COLLECTORS ....................................................................................... 13

8. SOLAR IRRADIATION .......................................................................................................................... 13

9. VOLUME OF HEAT TRANSFER FLUID .................................................................................................. 16

10. CONCEPTUAL SCHEMATIC .................................................................................................................. 17

11. CONCLUSIONS .................................................................................................................................... 20

12. BIBLIOGRAPHY .................................................................................................................................... 21

Table of Figures

Figure 1. Flat-plate solar collector efficiency vs evacuated tube efficiency at various temperature. ..........9

Figure 2. Parabolic Dish Collector .............................................................................................................. 10

Figure 3. Parabolic Trough Collector .......................................................................................................... 10

Figure 4. Heating fluid Efficiency ............................................................................................................... 11

Figure 5. Heating fluid minus ambient temperature efficiency ................................................................. 11

Figure 6. Efficiency with ambient temperature being 25 °C ...................................................................... 11

Figure 7. Schematic of Heating System ...................................................................................................... 17

Figure 8. Schematic of Heating System ...................................................................................................... 19

Appendixes

Appendix 1 _ Technical Information for Solar Collectors

Appendix 2 _ Calculations


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FEASIBILITY REPORT

1. INTRODUCTION

Having environmental perception and since I am used to ample sun light, taking advantage

of the solar energy in daily domestic application, I have decided to explore the possibility to

integrate the solar heating in the below specific industrial application.

The present feasibility report summarizes the outcome of my investigation carried out.

2. DESCRIPTION OF THE INDUSTRIAL OPERATION

A new LPG (Liquefied Petroleum Gas) Terminal will be constructed in Luka Ploče (port of

Ploče), in Croatia.

The purpose of the LPG Terminal is to import

LPG (mixture of propane & butane), pure

propane & pure butane products, to store them,

blend them as and if needed to the export LPG

specification and export them to sea going

medium & small size tankers / barges, road

trucks and rail train cars

The LPG will be normally delivered by Very Large Gas Carriers (VLGC) of DWT ≃ 58.000 tn,

LOA = ≃ 230 m ; BOA ≃ 37 m ; Max Draft 13 m.

DWT = Deadweight tonnage (the mass a ship can safely carry, it doesn’t include the ship’s weight) LOA = Length overall (max length of a vessel's hull, measured parallel to the waterline.) BOA = Beam, Overall (the width of the ship, measured at the widest point of the nominal

waterline) DRAFT = The vertical distance from the bottom of the keel to the waterline.

The vessels will be moored at the LPG Berth

of a new Jetty and will be unloaded with LPG

Marine Loading Arms (MLAs) installed at the

Jetty Loading Platform.


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2.1 CONDITIONS OF THE LPG AT THE GAS CARRIERS

The LPG storage at the gas carriers will be:

Either at fully refrigerated condition (in

the VLGC), at atmospheric pressure

(1,013 bara) with minimum storage

temperature -46°C (-50,8 °F), Or

At pressurized condition, at atmospheric

temperature (i.e. at around 12 to 15 bara,

at max 30°C to 40°C).

The LPG composition may vary.

Design Input = The most volatile LPG composition (design case composition) is “98%

propane + 2% ethane”, having boiling point -46 °C (-50,8 °F) at atmospheric pressure (1,013

bara).

2.2 STORAGE OF THE LPG AT THE TERMINAL

The LPG will be stored in the Terminal, at atmospheric temperature, in mounded pressurized

bullets (pressurized vessels). Mounded pressurized bullets are depicted in the below images:

2.3 DELIVERY OF THE LPG

The imported refrigerated LPG, during its transfer from the gas carriers to the mounded

pressurized bullets, will be heated from the transportation temperature of -46°C to the

(minimum) storage temperature of around +5°C, to avoid the operation of the pressurized

bullet in a wide temperature range (eg. -44°C, to +30°C), since such a difference in the

bullet's operating temperature can result to thermal / mechanical shocks and cycling loading

of the bullet’s material due to thermal variations.

The ship unloading flow rate is envisaged to be 2.000 m3/h. The LPG will be transferred

through pipelines from the Jetty to the mounded bullets.

It is expected that the delivery of the fully refrigerated LPG will be through batches of 44,000

m3. The delivery is predicted to take place approximately every two weeks (14 days).


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3. SCOPE OF THE INVESTIGATION

The scope of the present investigation is to explore whether it is feasible to utilize solar

energy in the heating process of the refrigerated LPG during its unloading.

The heating will be offered via heat transfer fluid, heated by solar collectors for the period

between two consecutive LPG batch deliveries (14 days).

The heated fluid will be heated during that period of 14 days in a closed circuit and stored in

a heat storage tank.

The heat from the heat transfer fluid to the LPG will be transferred during the LPG unloading

period of 22 hours.

The peculiarity of the project is that heat energy will be gathered for a long period of time (14

days) and transferred in a small span of time (22 hours). This is an elementary parameter

that influences the analysis.

The investigation analyses on the energy that the solar collectors receive from the sun.

4. HEATING REQUIREMENTS

Since it was not possible to find in the internet, readily available, the properties of the LPG

composition “98% propane + 2% ethane”, as a first approach, the below heat rate calculation

is based on pure (100%) propane having “boiling temperature” (liquid changes into vapor) =

-42°C (instead of -46°C). Reference: (API Technical Data Book)

a. The assumed delivery conditions of the propane are:

Storage temperature of the liquid propane in the VLGC, at atmospheric pressure =

= Boiling temperature of the propane = -42°C (-43,6 °F)

Density of the liquid propane at -42° C = around 585 kg/m3 (Specific gravity = 0,585)

Specific heat (Heat capacity) of the liquid propane at -42°C = 0,537 Btu/lb °F =

= 0,537 kcal/kg °C

Ship unloading flow rate: maximum 2.000 m3/h

b. The assumed heated propane’s conditions are:

Minimum Temperature of the heated propane (at the outlet of the heating system) =

+5 °C (+41°F)

Specific heat (Heat capacity) of propane at +5 °C: 0,598 Btu/lb °F = 0,598 kcal/kg °C

Notes:

The LPG properties were obtained from the “API Technical Data Book” (downloaded

from the internet).

See Appendix 2 “Calculations”.


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Heating Rate:

2nd thermodynamic law

The amount of heat rate gained by a substance, given its specific heat (cp), mass flowrate

(mflow) and the change in temperature (temperature difference) (ΔT), is given by the formula:

Q [kcal/hr] = mflow x cp x (ΔT) (kg/hr x kcal/kg°C x oC)

The mass flowrate = volumetric flow rate (m3/h) x density (kg/m3)

The mass flowrate to be heated is = The “volumetric flow rate” (2.000 m3/h) x the density of the imported LPG being at -42°C (585 kg/m3).

Heating Rate Q [kcal/h] =

= 2.000 m3/h x 585 kg/m3 x (+5 – (-42)) °C x ((0,537+0,598)/2) kcal/kg°C =

= 31.206.825 kcal/h = 36,29 MW (31.206.825 kcal/h x 0,000001163 MW / kcal/h =

= 36,29 MW).

Based on the ship unloading flow rate of 2.000 m3/h, the LPG transfer from the VLGC to the

mounded bullet, and thus the heating of the LPG, shall be performed during a period of 22

hours.

Considering the above, the total energy required to be transferred to a batch of 44.000 m3 of

light LPG (propane) is = 31.206.825 kcal/h x 22 h = 686.550.150 Kcal = 686.550,150 Mcal =

= 686,550150 Gcal

References:

Liquid “heat capacity”: API Data Book, Fig 7D1.1 (attached) in Btu/lb °F, versus temperature deg

F. (API Technical Data Book)

Liquid “specific gravity”: API Data Book, Fig 6A2.1 (attached), versus temperature deg F.

Internet search: (Standard: API - TECHNICAL DATA BOOK PETROLEUM REFINING)

Almost the same values were obtained, by extrapolation, from the Table A12 - Properties for the

liquid propane, in the page 17 of the attached document. (PROPERTY TABLES AND CHARTS

(SI UNITS))

http://www.engineeringtoolbox.com/temperature-d_291.html

http://www.engineeringtoolbox.com/density-specific-weight-gravity-d_290.html


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5. SOLAR HEATING

In order to be able to exploit solar radiation for heating the refrigerated LPG, it will be

necessary to install solar collectors suitable to transfer the solar radiant energy to a heat

transfer medium, and hence to the LPG.

Since the unloading of refrigerated LPG is a discontinuous operation, with idle periods

between two deliveries (14 days), it will be convenient to endeavor to accumulate the

collected solar energy in some sort of “heat storage fluid”, and have it available during the

reception of the LPG product into the Terminal.

The heat storage / heat transfer fluid need to be stored in insulated tank of suitable

volume, to avoid heat losses.

For the same amount of heat storage, high temperature of the heat transfer fluid will

allow reduced volume of the heat fluid and of the heat storage tank. The amount of heat

transfer fluid required is calculated in the paragraph 9. below.

Higher temperature of the heat transfer fluid will result to larger temperature differentials

between the temperature of the heat transfer fluid (Ti) with the atmospheric temperature

(Ta), which affect the efficiency of the solar collectors. See next paragraph 6.A.

The heat transfer fluid could be the DOWTHERM™ A fluid, which, as per the

manufacturer’s data is capable of withstanding temperatures as high as 400°C and it is

suitable to collect, transport and store heat. References: (DOWTHERM™), (Dow's

Leading Fluid Technology for Extreme Concentrated Solar Power Requirements)

Its Operating temperature range (for the liquid Phase) is = 12°C to 400°C (54°F to

750°F), as per manufacturer’s recommendation. Reference: (DOWTHERM™ A Capturin

Power from the Sun)

Another option for the heat transfer fluid is the THERMINOL 66 fluid that has an

operating temperature up to 345 °C. Reference: (Solutia)

For the purpose of the present application 300°C temperature could be selected as the

max temperature for the heat storage fluid / heat transfer fluid.

The following paragraph elaborates the selection of the type of the solar collector.


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6. SOLAR THERMAL TECHNOLOGIES/SOLAR COLLECTORS

In general, there are two groups of solar thermal technologies that could be used for the

subject industrial heat application

These are the:

A. CONVENTIONAL SOLAR SYSTEMS and

B. SOLAR CONCENTRATORS.

A. CONVENTIONAL SOLAR SYSTEMS

The conventional solar systems are the most frequently used solar collector systems in

domestic application.

Such systems are the:

a) Flat-Plate Collectors (FPC) and

b) Evacuated Tube Collectors (ETC).

With the commercially available FPCs and ETCs, used in residential applications, heat of

lower temperature than 80°C can be easily provided.

Conventional ETCs however, can provide temperature levels of up to 120°C and are

more suitable for use in in cold climates.

For medium temperature processes; new advanced collector designs have been

successfully developed.

Ultra-high vacuum FPCs or ETCs with concentrators, being more expensive than the

conventional FPCs and ETCs, can generate temperatures of up to 100°C for FPCs and

up to 200°C for ETCs.

The higher efficiency of the ETCs makes them preferable when the available space for

the collectors’ installation is limited.

Details regarding the FPCs and ETCs are included in the Appendix 1 attached herewith.

The performance of the FPCs and ETCs depends on the temperature (Ti) of the fluid to

be heated entering into the heat collector (heat transfer fluid), compared to the ambient

temperature (Ta).

The below graph indicates the Thermal efficiencies of the conventional Flat Plate &

Evacuated Tubes solar collectors.


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Thermal Efficiencies - Comparison of Flat Plate & Evacuated Tubes Solar Collectors

50oC = 122oF

65oC = 149oF

90oC = 194oF

Source: https://blog.heatspring.com/solar-thermal-flat-plate-or-evacuated-tube-collectors/

If FPCs and ETCs are placed on the same location, one next to the other, it is noticed

that their performance is based on the difference between the temperature (Ti) of the

entering fluid to be heated (heat transfer fluid) and the ambient temperature (Ta).

The collectors’ efficiency is decreased in higher differential between the Ti and Ta.

SUMMARY on the Conventional Solar Systems

Flat Plate Collector Evacuated Tube Collectors

Temperature level that

can be achieved (Ti)

Conventional FPCs: 80 °C

Advanced design FPCs: up to 100°C

Conventional ETCs: even 120 °C

Advanced design ETCs: up to 200°C

Thermal Efficiency

It is strongly affected by the

temperature difference between

the heat transfer fluid Ti and the

ambient Ta (Ti - Ta). Thus the max

practically achievable storage

temperature is limited.

As the temperature variance

(Ti - Ta) increases (e.g. in colder

temperatures), evacuated tubes

become more efficient.

Suitable for use in cold climates.

Both collectors have a globally low efficiency: Approximately 40 – 50% in domestic

applications and much lower if they operating at high temperatures (high Ti).

(Ti): Temperature of the Heat Transfer Fluid

Figure 1. Flat-plate solar collector efficiency vs evacuated tube efficiency at various temperature.

https://blog.heatspring.com/solar-thermal-flat-plate-or-evacuated-tube-collectors/


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B. SOLAR CONCENTRATORS

The solar concentrators for the subject application include mainly:

a) the parabolic dish collectors,

b) the linear parabolic trough collectors and

c) the linear Fresnel collectors.

a) Parabolic Dish Collector

The parabolic dish concentrating systems

use parabolic dish shaped mirrors to focus

incoming solar radiation onto a receiver

that is positioned at the focal point of the

dish. Fluid in the receiver is heated to high

temperatures (around 750oC or more). This

fluid is then used to generate electricity in a

small Stirling cycle engine, which is

attached to the receiver. For details

regarding the Stirling engine please refer to

the Appendix 1 attached herewith.

The parabolic dish collectors can generate temperatures of 400°C, 750 °C or even

1000 oC.

The parabolic dish systems achieve high efficiencies for converting solar energy to

electricity in the small-power capacity range applications.

Details regarding the above collector are included in the Appendix 1 attached

herewith.

b) Parabolic Trough Collector

Parabolic-trough concentrating systems

can provide hot water and steam, and

are generally used in commercial and

industrial applications.

In the solar field, cold “heat transfer fluid” comes in,

picks up the heat collected by the trough and exits at a

high temperature.

Details about the above collector are included in the Appendix 1 attached herewith.

Figure 2. Parabolic Dish Collector

Figure 3. Parabolic Trough Collector


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Thermal Efficiency of a Parabolic Trough Collector

Thermal efficiency of a parabolic trough collector is the ratio of energy collected by the

heating fluid to the direct normal solar radiation incident upon the collector aperture.

Collector efficiency versus the

difference between the heating

fluid temperature (Thtf) and the

ambient temperature (Tamb) at

which the receiver heat loss

was measured, divided by

radiation.

From the above diagrams it is evident that as the temperature of the heat transfer fluid

increases the collectors’ efficiency drops. Moreover, the efficiency depends on the irradiation

level (W/m2).

References: (Kutscher, Burkholder and Stynes) (Montes, Abánades and Martínez-Val )

Figure 4. Heating fluid Efficiency Figure 5. Heating fluid minus ambient temperature efficiency

Figure 6. Efficiency with ambient temperature being 25 °C


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c) Linear Fresnel collectors

The Linear Fresnel collectors are similar to the parabolic trough collectors, except for the

mirrors which are placed on a horizontal surface at different angles to a fixed receiver

located several meters above the mirror field.

Optical efficiency of a typical linear Fresnel reflector system can reach 70%, and it is,

however, still inferior to that of a parabolic trough system which is in the range of 75 –

80%.

Details regarding the above collector are included in the Appendix 1 attached herewith.

SUMMARY on the Solar Concentrators

Considering the above and bearing in mind the similarity of the Parabolic Trough collectors,

with the Linear Fresnel collectors having less optical efficiency than the parabolic trough

collectors, the below Table summarizes the Temperature level and the Efficiency of the

Parabolic Dish Collectors and Parabolic Trough Collector

Parabolic Dish Collector Parabolic Trough Collector

Temperature level that

can be achieved (Ti) 400°C, 750 °C or even 1000 oC 300°C (or more)

Thermal Efficiency

High efficiencies for converting

solar energy to electricity in

small-power capacity range.

In the range of 70 % to 75%

(Ti): Temperature of the Heat Transfer Fluid

Table 1. Summary between Parabolic Dish and Trough Collectors


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7. CONCLUSION ON THE SOLAR COLLECTORS

Comparing the Conventional Solar Systems and the Solar Concentrators:

The Temperature level of the heat transfer fluid (Ti) that can be achieved with the

Parabolic Trough Collectors is significantly higher than the temperature level achieved

with the Conventional Solar systems. Also, this temperature is not as high as the

temperature achieved with the Parabolic Dish Collectors.

The Parabolic Trough Collectors have significantly higher efficiency than the efficiency of

the Conventional Solar Systems.

Based on the above, the Parabolic Trough Collectors, capable to achieve 300°C for the heat

transfer fluid, and having an efficiency of 70% (conservative value) have been considered as

the appropriate solar collectors for the subject application.

8. SOLAR IRRADIATION

Table 2. Solar irradiance data for Port Ploče

Month

Air

tem

pe

ratu

re [

°C]

Average daily solar irradiance of a surface

directed to the south [kWh/m2]

Horizontal surface (0°)

Optimally sloped surface (29°)

To

tal

Dis

pe

rse

d

Dir

ect

To

tal

Dis

pe

rse

d

Dir

ect

Re

fle

cte

d

January 6,9 1,67

0,85 0,82 2,58 0,80 1,76 0,02

February 8,1 2,60

1,16 1,44 3,63 1,08 2,51 0,03

March 10,6 3,77

1,70 2,07 4,49 1,59 2,85 0,05

April 13,8 5,08

2,14 2,94 5,36 2,00 3,29 0,06

May 18,6 6,19

2,50 3,69 6,01 2,34 3,58 0,08

June 22,1 6,99

2,51 4,48 6,52 2,35 4,08 0,09

July 24,9 6,98

2,36 4,62 6,63 2,21 4,33 0,09

August 24,4 6,13

2,12 4,01 6,28 1,99 4,22 0,08

September 20,8 4,67

1,71 2,96 5,40 1,60 3,74 0,06

October 16,0 3,28

1,31 1,97 4,39 1,22 3,13 0,04

November 11,1 1,90

0,94 0,96 2,83 0,88 1,93 0,02

December 7,7 1,44

0,75 0,69 2,31 0,71 1,59 0,02

Total annual

[MWh/m2] -

1,55

0,61

0,93

1,72

0,57

1,13

0,02

The Table: “Table 2. Solar irradiance data for Port Ploče’’, above, was obtained during

my stay in Zagreb, Croatia.


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The above Table reports the average daily solar radiation on a monthly basis for the Ploče

location.

Considering that:

the accumulation of solar heat will exploit the solar radiation collected during 14 days,

that the energy uptake efficiency of the collectors may be assumed as 70%, and

that the installed collectors surface is 1000 m2,

the maximum expected solar heat contribution to the heating of fully refrigerated LPG during

the LPG transfer from the VLGC is:

a) Solar Contribution - During July (month of maximum irradiation)

Q= 14days x 6,63kWh/day m2 x 0,7 eff. x 1.000 m2 surface / 1000 kW/MW =

= 64,974 MWh =

= 64,974 MWh x 859,845 Mcal / MWh = 55.868 Mcal = 55,868 Gcal

b) Solar Contribution - During December (month of minimum irradiation)

Q= 14days x 2,31kWh/day m2 x 0,7 eff. x 1.000 m2 surface / 1000 kW/MW =

= 22,638 MWh =


(1 MWh = 859.845 kcal = 859,845 Mcal = 0,859845 Gcal)


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c) Solar Contribution - Annual Average

The average contribution of solar heating can be estimated based on the weighted

“average solar irradiation”:

Table 3. Average Solar Irridation

KWh/day m2 days

KWh/month

m2

Jan 2,58 x 31 = 79,98

Feb 3,63 x 28 = 101,64

March 4,49 x 31 = 139,19

April 5,36 x 30 = 160,80

May 6,01 x 31 = 186,31

June 6,52 x 30 = 195,60

July 6,63 x 31 = 205,53

Aug 6,28 x 31 = 194,68

Sept 5,4 x 30 = 162,00

Oct 4,39 x 31 = 136,09

Nov 2,83 x 30 = 84,90

Dec 2,31 x 31 = 71,61

Total 365 1.718

Average Solar Irradiation = 4,708

Q= 14days x 4,708kWh/day m2 x 0.7 eff. x 1.000 m2 surface / 1.000 kW/MW =

= 46,138 MWh =



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Summary

Based on the above solar heat values, the percentage wise (%) contribution of the solar

heating, to the maximum heat required to increase the temperature of a 44.000 m3 propane

batch from fully refrigerated temperature (- 42°C) to storage temperature (+5°C) is:

Max Solar Contribution (during July)

55,868 Gcal / 686,550150 Gcal = 8,13%

Min Solar Contribution (during December)

19,465 Gcal / 686,550150 Gcal = 2,83%

Average Solar Contribution (during the Year)

39,672 Gcal / 686,550150 Gcal = 5,8%.

9. VOLUME OF THE HEAT TRANSFER FLUID

The Heat Transfer Fluid required is calculated as follows, considering:

Mass (kg) = Total duty (Kcal) / [fluid heat capacity (kcal/kg°C) x ΔT (°C)]

Operating Temperature range ΔT (°C) of the Heat Transfer Fluid for the subject

application = 50oC to 300oC

The properties of Dowtherm A are provided in the Supplier’s brochure:

Dowtherm A - Specific Heat

At 50oC = 1,658 kJ/kg.K

At 300oC = 2,359 kJ/kg.K

Average value = (1,658 + 2,359 kJ) / 2 = 2,0085 kJ/kg.K = 0,48 kcal/kg°C

Dowtherm A - Density at 300oC = 806,8 kg/m3 = around 807 kg/m3

For maximum solar radiation the volume required is:

55,868 Gcal x 106 kcal / Gcal / (0,48 (kcal/kg°C) x (300-50) (°C) = 465.566,7 kg

At max T of 300°C the density is 807 kg/m3 the volume is = 577 m3

The properties of Therminol 66 are provided in the Supplier’s brochure:

Therminol 66 - Specific Heat

At 50oC = 1,665 kJ/kg.K

At 300oC = 2,569 kJ/kg.K

Average value = (1,665 + 2,569 kJ) / 2 = 2,117 kJ/kg.K = 0,505 kcal/kg°C

Therminol 66 - Density at 300oC = 808,5 kg/m3 = around 809 kg/m3

For maximum solar radiation the volume required is:

55,868 Gcal x 106 kcal / Gcal / (0,505 (kcal/kg°C) x (300-50) (°C) = 442.518 kg

At max T of 300°C the density is 809 kg/m3 the volume is = 547 m3

An allowance on this volume should be added to account for piping circuits and heat

exchanger’s volumes.

An evaluation of the cost for the storage volume versus the savings in fuel consumption for

heating, during the hot season should be made to optimize the storage capacity.


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10. CONCEPTUAL SCHEMATIC

A preliminary Conceptual Schematic of the proposed Solar Heating System is indicated here

below.

The Solar Heating System will include the following equipment / components:

Parabolic Trough Solar Collectors. An insulated Heat Storage tank, for the storage of the heat fluid / heat transfer fluid (HF).

A Pump for the recirculation for the HF between the heat storage tank and the solar collectors.

A Heat Exchanger (H.E.)

A Pump for the recirculation of the HF between the heat exchanger and heat storage tank.

Insulated piping, valves, controls.

Figure 7. Schematic of Heating System


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The contribution of the solar heating to the LPG heating system will be carried out in two

stages:

Stage 1

a. The heat transfer fluid will be heated by the parabolic trough solar collectors during the period of two consecutive LPG batch deliveries (14 days duration).

b. The Recirculation Pump #1 will recirculate the heat transfer fluid between the heat storage tank and the solar collectors (14 days duration).

c. The heated transfer fluid will be stored within the insulated Heat Storage Tank. The stored heat will be used during the heating process of the refrigerated LPG i.e. during the LPG’s ship unloading operation (22 hrs).

Stage 2

a. The Recirculation Pump #2 will recirculate the heat transfer fluid between the heat storage tank and the Heat Exchanger (22 hrs).

b. The flow of the heat transfer fluid will be adjusted by a Control Valve, based on the temperature which is set at the Temperature Controller & the measured temperature of the heated product.


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Figure 8. Schematic of Heating System


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11. CONCLUSIONS

The solar heat can contribute to the LPG heating, with an average annual solar contribution of

around 5,8% percentage, for installed collectors’ surface of 1000 m2.

It goes without saying that the above percentage of 5,8% will be increased proportionally, by

increasing the installed collectors’ surface.

The space availability for the installation of the solar collectors and the financing of the upfront

investment costs for the: solar collectors, heat storage tank, heat exchanger, pumps for the

recirculation of the heating fluid, are the key barriers in the decision to be made for the use of

the solar energy.

In addition, the operational cost of the recirculation pump #1, operating continuously to

recirculate the heat transfer fluid between the heat storage tank and the solar collectors (14

days), should be taken into account.

The costs of solar heat for industrial process heat depend on process temperature level,

demand continuity, project size and the level of solar radiation of the site.

Reference: (IRENA)


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12. BIBLIOGRAPHY

API Technical Data Book. Vers. 10. n.d. Software Package. August 2017.

<http://www.apidatabook.com/>.

Dow's Leading Fluid Technology for Extreme Concentrated Solar Power Requirements. 2017. Web. 2017.

<http://www.dow.com/heattrans/csp/index.htm>.

DOWTHERM™. 2017. The Dow Chemical Company. Web. 2017.

<http://www.dow.com/heattrans/products/synthetic/dowtherm.htm>.

"DOWTHERM™ A Capturin Power from the Sun." 2017. The Dow Chemical Company . The Dow Chemical

Company . Web. 2017.

<http://msdssearch.dow.com/PublishedLiteratureDOWCOM/dh_0931/0901b803809318d7.pdf

?filepath=heattrans/pdfs/noreg/176-01621.pdf&fromPage=GetDoc>.

IRENA, IEA-ETSAP. "Solar Heat for Industrial Processes." January 2015. IRENA International Renewable

Energy Agency . IEA-ETSAP and IRENA. Web. 2017.

<http://www.irena.org/DocumentDownloads/Publications/IRENA_ETSAP_Tech_Brief_E21_Solar

_Heat_Industrial_2015.pdf>.

Kutscher, Charles, Frank Burkholder and Kathleen J Stynes. Generation of a Parabolic Trough Collector

Efficiency Curve From Separate Measurements of Outdoor Optical Efficiency and Indoor Receiver

Heat Loss. 29 November 2011. American Society of Mechanical Engineers. Web. 2017.

<http://solarenergyengineering.asmedigitalcollection.asme.org/article.aspx?articleid=1456277>

.

Montes, J. M., et al. "Solar múltiple optimization for a solar-only thermal power plant,." 2009. Archivo

Digital UPM. E.T.S. I Industriales . Web. 2017.

<http://oa.upm.es/5304/2/INVE_MEM_2009_69069.pdf>.

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