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Solar Thermal

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Concept Note on Solar Thermal
Technology Description


CONCENTRATING SOLAR THERMAL POWER (CSP)

CSP is used to produce electricity (sometimes called solar thermoelectricity, usually generated through steam). Concentrated-solar technology systems use mirrors or lenses with tracking systems to focus a large area of sunlight onto a small area. The concentrated light is then used as heat or as a heat source for a conventional power plant (solar thermoelectricity). The solar concentrators used in CSP systems can often also be used to provide industrial process heating or cooling, such as in solar air conditioning.

Concentrating technologies exist in four optical types, namely parabolic trough, dish, concentrating linear Fresnel reflector, and solar power tower. Parabolic trough and concentrating linear Fresnel reflectors are classified as linear focus collector types. Dish and solar tower as of the point focus type. Linear focus collectors achieve medium concentration (50 suns and over), and point focus collectors achieve high concentration (over 500 suns) factors. Although simple, these solar concentrators are quite far from the theoretical maximum concentration. For example, the parabolic-trough concentration gives about ​1⁄3 of the theoretical maximum for the design acceptance angle, that is, for the same overall tolerances for the system. Approaching the theoretical maximum may be achieved by using more elaborate concentrators based on nonimaging optics.

Different types of concentrators produce different peak temperatures and correspondingly varying thermodynamic efficiencies, due to differences in the way that they track the sun and focus light. New innovations in CSP technology are leading systems to become more and more cost-effective

Solar Heat for Industrial Processes
Solar thermal can fulfill a substantial amount of heat demand in industrial and agricultural food processes within any given country and irrespective of the geographical location. In developed economies, solar thermal can provide technically about half of this energy consumption by supplying hot water and steam in a temperature range of up to 400°C. In developing countries, especially in those where agriculture, the textile, brick and food processing industries are important sub-sectors, solar thermal energy can provide hot air and hot water needed for curing, drying, dyeing, washing, boiling, pasteurisation and sterilisation.

In general, there are three groups of solar thermal technologies that are useful for industrial process heat: solar air collectors, solar water systems, and solar concentrators.

  • Solar air collectors are found primarily in the food processing industry to replace gas- or oil-based drying or to reduce food spoilage due to open- air drying. They can be built locally, and their cost depends on local building materials and labour.
  • Conventional solar water systems, like flat-plate collectors (FPC) or evacuated tube collectors (ETC), are primarily used in residential applications, but they can readily be installed on industrial rooftops to provide heat demand of up to 125°C. More than one hundred systems exist around the world. A small number of large international companies sell these technologies, but the majority of solar water heating systems are manufactured locally by small- and medium-size enterprises. This is especially the case in countries like Brazil, China, South Africa and Turkey where the costs are three to ten times lower than in the United States or in European countries. A number of more advanced FPC and ETC designs are currently on the market and can generate temperatures of up to 250°C; however, they are also more expensive than conventional FPC and ETC.
  • Solar concentrators include parabolic dish collectors, linear parabolic trough collectors and linear Fresnel collectors. In India, local manufacturers sell mainly parabolic dish collectors that can generate temperatures of up to 400°C. Around 80 commercial projects are installed in India, mostly for community solar cooking. The other two types of solar concentrators are similar to those used to produce concentrated solar power. Around twenty commercial systems currently exist around the world.

Solar Concentrators for Medium Heat (150°C- 400°C)

For medium temperature process heat applications, some advanced FPC designs with ultra-high vacuums are available to provide temperatures up to 200°C. However, the main technology used for medium temperature heat are solar concentrator technologies. In the simplest case, compound parabolic concentrators (CPCs) are fitted behind the vacuum tubes of the ETC, reflecting both direct and diffuse sunlight onto the absorber (also called CPC vacuum tubes). Similar concentrators can be used for FPC. Depending on the configuration of the mirror, concentration factors of up to 4:1 can be achieved, although typically CPC concentration is around 1.5 or lower. Combined with ultra-high vacuum technology, these ETC can provide nominal temperatures up to 200°C. Other solar concentrators for process heat are similar to technologies used to produce concentrated solar power (CSP), except that in most cases, they are smaller in size (from 10 kW to 2 MW). Instead of using the heat to produce power however, the heat is directly used in industrial processes. Examples of solar concentrators are parabolic dishes (with flat or curved glas, fixed or moving focus), parabolic trough concentrators and Linear Fresnel collectors. The concentrators can use various shapes (e.g. troughs, cylindrical discs,mirror-strips) to concentrate the sunlight onto the absorber.
Parabolic dishes:
Parabolic dishes were already used in antiquity, and consist of a parabolic reflec­tor dish focusing sunlight onto the focal point in front of the dish. The dish can consist of flat mirrors attached to wooden, steel or aluminium frames. Some dishes are static and need to be manually adjusted (2-3 times a day) to follow the sun, while others track the sun automatically. One particular design is the Scheffler dish, which was popularised in India. Another example is the ARUN-160 dish, a two-way tracking parabolic dish with an aperture area of 160 m2, weighing around 20 tonnes and generating 100-120 kg of steam per hour (between 80-100 kW of thermal output) (Clique Solar, n.d.).
Parabolic trough collectors use curved glass to focus the sunlight on heat receivers (i.e. steel tubes or evacuated glass tubes) placed on a focal line.
Linear Fresnel collectors:
Linear Fresnel collectors are similar to parabolic trough collectors, except for mirrors that are placed on a horizontal surface at different angles to a fixed re­ceiver located several meters above the mirror field. Furthermore, for industrial process heat production, Linear Fresnels often need to be adapted to available rooftop and land areas around the industrial site, resulting in different lengths of collector rows and different orientations. These high-concentration collectors can produce temperatures up to 400°C and are extremely interesting for industrial process heat applications. Renewed interest in these technologies has led to new prototype development in several research institutes around the world and they are becoming more popular, especially for district heating and cooling.
The choice of heat transfer fluid becomes important for medium temperature requirements in solar process heat technologies. Direct systems (or open-loop systems) can use water or air as the heat transfer fluid directly in their processes. However, air has a low heat capacity and water a low boiling point and may be corrosive or deposit minerals in the collector. In indirect systems (or closed-loop systems), some alternative heat transfer fluids are glycol and hydrocarbons (with lower freezing points suitable for cold climates), refrigerants (with high thermal capacity but with low boiling points), molten salt (with typical melting point above 140°C and high thermal capacity), or advanced heat transfer fuels (enhanced performance but also more costly). Other considerations are the costs of the heat transfer fluid, degradation (due to higher temperatures) and the viscosity (higher viscosity means more energy required for pumping).

The selection of an appropriate solar collector basically depends on five factors: 1) operating temperatures; 2) thermal efficiency; 3) energy yield; 4) cost; and 5) the space occupied. Other aspects, such as the possibility of roof integration or system size, also have to be considered. Furthermore, the choice depends on the technology used to provide the heating or cooling services.

 

 

 Global scenario of adoption or demonstration of the technology

The cumulated solar thermal capacity in operation by end of 2017 was 472 GW (675 million square meters). Compared to the year 2000 the installed capacity grew by the factor 7.6. The corresponding annual solar thermal energy yield in 2017 amounted to 388 TWh, which correlates to savings of 41.7 million tons of oil and 134.7 million tons of CO2.

Despite these achievements, the global solar thermal market has faced challenging times in recent years. This is especially evident in the large markets in China and Europe where the traditional mass markets for small-scale solar water heating systems for single family houses and apartment buildings are under market pressure from heat pumps and photovoltaic systems. In total, the global market declined by 4.2 % in 2017. Positive market developments were recorded in India (26 %), Mexico (7 %),and in Turkey (4 %). In contrast to the small-scale solar water heating systems, the megawatt-scale solar supported district heating systems and industrial applications have gained increasing interest all over the world in recent years and several ambitious projects have been success fully implemented.

By the end of 2017 about 300 large-scale solar thermal systems (>350 kW; 500 m²) connected to district heating networks and in residential buildings were in operation. The total installed capacity of these systems equaled 1,140 MW (1,630,415 m²), excluding concentrating systems that add 110,929 m².

In 2017, nine large-scale solar thermal systems with about 35,000 m² (24.5 MW) were installed in Europe. Outside Europe, 5.9 MW (8,444 m²) were installed and one concentrating system in Tibet with a collector area of 9,000 m². About 75 % of the new collector area installed in Europe is from two new large systems in Den mark and three extensions added to Danish systems. About 92 % of the installed capacity in stalled outside Europe has been installed in China.

The world’s largest plant for solar district heating is located in Silkeborg, Denmark and has an installed capacity of 110 MW (156,694 m² flat plate col lec tors). The start of operation of this plant was in December 2016.

Important to note is that in 2016 and 2017 three parabolic trough collector fields were installed for feeding into district heating networks in Denmark and China. The concentrating collector area of these three systems installed adds up to 110,929 m².

Solar Heat for Industrial Processes (SHIP) continues to be a growing market. A number of promising projects have been implemented in the last couple of years ranging from small-scale demonstration plants to very large systems with 100 MW capacity. At least 624 SHIP systems, totalling 608,994 m² collector area, were in operation at the end of the year 2017.

2017 was a record year for SHIP installations – 124 new larger systems, total ling 192,580 m² collector area, started operating. With this, the documented world total grew in 2017 by 25 % in number of installed plants and by 46 % by installed collector area. The world’s largest solar process heat application began operation in February 2018 at the Amal oil field located in the south of the Sultan ate of Oman. The Miraah parabolic trough plant with a total capacity of over 100 MW delivers 660 tons of steam per day for the extraction of viscous or heavy oil as an alternative to steam generated from natural gas.

Global concentrating solar thermal power (CSP) capacity reached 4.9 GW in 2017, with South Africa being the only country to bring new CSP capacity online (100 MW). However, at year’s end about 2 GW of new plants was under construction; China (300 MW being built) and Morocco (350 MW) were particularly active. An estimated 13 gigawatt-hours of thermal energy storage (TES) was operational, and most new plants are incorporating TES. Spain remained the global leader in existing CSP capacity – followed by the United States – with Spanish CSP plants achieving record electricity generation in 2017. The year also saw record low CSP tariffs being bid and/or awarded in competitive tenders in Australia, Chile and the United Arab Emirates, where a 700 MW CSP tender was awarded. CSP with TES emerged as a viable competitor to fossil fuel thermal power plants. Price reductions were driven by competition as well as by technology cost reductions aided by ongoing research and development activity in the sector.

 

 

Indian Scenario

India added 0.9 GW (1.28 million m2) in 2016, an increase of 6% relative to 2015.The market appears to be bouncing back, following a temporary reduction in demand that resulted from the suspension of India’s national grant scheme in 2014. The share of imported vacuum tubes grew to 88% (up from 82% in 2015).This segment included an increasing number of vacuum tubes backed with aluminium mirrors (so-called compound parabolic concentrators), which are used primarily for industrial process heat applications. This trend was supported by a national 30% capital subsidy scheme for concentrating solar thermal technologies, which has reduced the payback times to three to four years for manufacturing businesses. Only 0.11 GW of flat plate collectors (down from 0.15 GW in 2015) was sold by the handful of manufacturers that remains in India
At the end of 2012,India had 7 967 m² of solar concentrator systems for solar cooling and a total of 27 972 m² of solar concentrator-based systems for industrial heating applications (REN21, 2014)
India was the lead country and 61% of its solar thermal capacity was used for industrial process (including community cooking); in total, 78 commercial applications of solar concentrators (all parabolic dish collectors) were installed (88% for solar cooking) (Sun & Wind Energy, 2014). Furthermore, there are currently around eight projects using FPC, ETC and Linear Fresnel collectors for solar process heating (AEE INTEC & PSE, 2014) in operation. As the largest milk producer in the world, India’s dairy sector is also one of the most interesting application areas where up to 13% of process heat could be supplied by solar thermal (GIZ,2011). Out of the top ten companies supplying solar process heating plants, four are parabolic dish suppliers from India. An important driver for the deployment of solar concentrators in India are the capital subsidies (up to 60%) provided by the Indian Government and a UNDP-GEF project (Sun Focus, 2014).

Highlights of Projects commissioned in India for Thermal Process Heating:-

 

  • Steam Cooking System for 50000 people using Scheffler Dishes at New Sai Prasadyala, Shirdi

Location: Shirdi, Maharashtra
Type of Installation: Scheffler Dishes
Configuration: 1168m2 (16 m2 x 40 No’s)
Supplier: Gadhia Solar Energy Systems Pvt. Ltd.
Application: Cooking
System Details: The total system has an area of 1168 m2 comprising of 40 concentrators with 16 m2 capacities each. The system was commissioned during 2009 by Gadhia Solar Energy Systems Pvt. Ltd. Prior to the implementation of the CST system the establishment was using LPG as a fuel for its end use consumption. The system is integrated with its existing process. The project is set up at a cost of Rs. 106.2 Lakh with grant availed from MNRE of the order of Rs. 58.40 Lakh.

Timings & System Application Details: The system operates for 3 hours for preparation of breakfast. The daily quantum of food is around 200 kg of Rice. The system is functioning well. Usage of the system is approximately 4-5 hours / day and around 300 days in a year that also depends upon the availability of sunlight.

 

Steam Generation: 2600 kg/d Operating Temperature & Pressure: 170°C & 8 kg/cm2
Type of Fuel Saved: LPG Quantity of Fuel Saved: 13 cylinders/day
Functionality & Key Issues of Non-Operation: Operational


* As on 31/03/2017.

 

 

Technical Specifications


Application

Smart Kitchen for Boiling, Frying and Baking

Energy Output

The MWS SmartKitchen ™ system is designed to provide energy for cooking
which is based on the information provided by the customer.

Fuel Firing system

Solar + LPG hybridized based Thermic fluid heating.

Cooking methodology

Closed loop header-based Jacketed vessel, No-Water, No Flame Kitchen

Application of heat

Heat generated through Solar + LPG hybridized based Thermic Fluid (TF) System shall be used for boiling, frying & baking.

The schematic layout is shown below. Note that this is a sample picture of equipment arranged inside the kitchen. During solar hours, the incoming return oil from the vessels at reduced temperature will input solar field to gain the heat at desired temperature and then feed into LPG heater. Solar field will add the requisite ▲T based on solar radiation availability, and any shortfall from solar shall be made up by LPG based TF heater to provide the required temperature for cooking. During non-solar hours, a 3-way control valve will by-pass the solar field to isolate solar field.

 


SOLAR FIELD DESCRIPTION

S. No

Details

Sub Details

Technical Requirement

  1.  

General

Solar Field

Solar Dish

Process Fluid

Thermic Fluid (NSF Approved)

Peak Operating Temperature of Thermic Fluid

250 0C

Peak Operating Pressure of Thermic Fluid

10 kg/cm2 (g)

  1.  

Concentrator

Reflector Area

Minimum for transferring 20 kW energy to Thermic fluid at peak DNI of 800 W/m2

Reflector Material

Back polished, Low iron content glass reflector / Solar Grade Metallic / Non Metallic Reflector

Reflectivity

≥ 90 % (bidder to provide manufacturer / test lab certification for at least one sample)

Material of Frame Structure

MS (Galvanized / Painted)

Survival wind speed

As per Wind zone

  1.  

Receiver

Receiver Material

Carbon Steel tube

Hot Insulation

Mineral Wool & Aluminum Cladding

  1.  

Tracking System

East-West Tracking

  • Remote Manual AND
  • Automatic

North-South Tracking

  • Manual (minimum requirement) OR
  • Remote Manual AND
  • Automatic (preferable)

Parking

  • Remote Manual AND
  • Automatic (preferable)

De- focusing & Re- focusing

Automatic (preferable)

Tracking accuracy

+/- 0.5 degree

  1.  

Accessories

Solar Dish Cleaning System

Required

Support structure, Maintenance Platform and Ladder

MS (Galvanized / Painted)

THERMIC FLUID HEATER (TFH)

Specifications

S. No.

Details

Technical Requirement

 

Thermal Capacity

1,00,000 Kcal / Hr (minimum)

 

Fuel

LPG

 

Duty

Multiple Start / Stop every day

 

Process Fluid

Thermic Fluid

 

Operating Thermic Fluid Temperature

250 0C

 

Type

Vertical / Horizontal

 

Number of Pass

3 (Minimum)

 

Efficiency

85% (Minimum)

 

Burner

Mono block

 

Burner Control

Automatic

 

Igniters

High Energy Arc

 

Flame Sensing

Required

 

Air Blower

Centrifugal

 

Chimney

Required (to be extended above the canopy height)

 

TFH Start / Stop

Manual from Local Control Panel and Automatic

 

TFH Tube Material

ASTM 106 Gr-B Seamless

 

Hot Insulation

Mineral Wool & Aluminum Cladding

 

Electric Supply

3Phase, 415 VAC

 

Safety Protection (Minimum)

  • TFH Flow – LO,
  • TFH Outlet Temperature – HI,
  • TFH Stack Temperature – HI,
  • Flame Failure,
  • Power Failure

THERMIC FLUID PUMP (TFP)

 

Fluid

Thermic Fluid

 

Operating Temperature

250 0C

 

Type

Preferably Canned Motor Pump / Magnetic Drive Pump

 

Lubrication

Self (Preferable)

 

Cooling

Self (Preferable)

 

Flow & Head

Suitable for Thermic Fluid Heater & Solar Field

 

Motor

3Phase, 415 VAC

 

EXPANSION TANK

 

Volume

500 Litres (Minimum)

 

Material

MS

 

Openings & Ports (Minimum)

  • Thermic Fluid Inlet
  • Thermic Fluid Outlet
  • Vent
  • Drain
  • Level Switch

 

Hot Insulation

Nano insulate paint coating (minimum 10 coats) with Mineral Wool & Aluminum Cladding OR PUF insulation with Aluminum Cladding

 

Support structure, Maintenance Platform & Ladder

MS (Galvanized / Painted)

 

Miscellaneous

  • Drain and vent shall be routed to a separate MS vessel
  • All round enclosure wall of adequate size and height in order to accommodate thermic fluid spillage.

THERMIC FLUID

 

Operating Temperature

250 0C

 

Operating Pressure

Ambient

 

Boiling Temperature

> 310 0C

 

Type

Thermic Fluid (USFDA Approved)

 

Accessories

Hand Pump for transfer of thermic fluid

 

Quantity of thermic fluid

This is in Customer's scope as per the site layout

COOKING VESSEL

 

Boiling Vessel

  • Material: SS 304 or better
  • Tilting arrangement
  • Cleaning arrangement
  • Support Structure: MS (painted)

 

Frying Vessel

  • Material: SS 304 or better
  • Tilting arrangement
  • Cleaning arrangement
  • Support Structure: MS (painted)

 

Hot Plate

  • Material: 16 mm (preferred) MS
  • Support Structure: MS (painted)

PIPE WORK

 

Pipe

  • Material: Carbon Steel
  • Type: Seamless
  • Grade: ASTM A-106 Gr B
  • Size: 15/25/50 NB (As per P&ID)

 

Pipe Flange

Raised face (Preferable Finish - RMS 125)

 

Flange Gaskets

Spiral-wound (SS-304 & Flexible graphite filler)

 

Flange Bolt

ASTM A-193 Grade B7 (preferable)

 

Flange Nut

ASTM A-194 Grade 2H (preferable)

 

Flange Washer

ASTM F-436 (preferable)

 

Valve

  • Type: Piston / Gate / Globe / Ball (As per P&ID)
  • Rating: 150 or above
  • Size: 15/25/50 NB (As per P&ID)
  • Material: Cast or forged carbon steel
  • Stem Packing; Graphite or expanded/filled PTFE
  • End: SE / BE
  • Provision for hot operation of valves

 

CONTROL AND INSTRUMENTATION

  • The STCS operation shall be done from a LCP-Local control panel.
  • Training program for operation shall be conducted before handover of the plant.
  • Temperature Transmitter, Level Transmitter: Honeywell, Yokogawa, ABB
  • Pressure Gauge, Temperature Gauge: H.Guru, WIKA, NAGANO KEKI, Goa, Pyro

As appropriate, all the above instruments shall be provided with isolation valves, thermo well, manifold etc.
CONTROL AND OPERATION PHILOSOPHY:
STCS will operate in full functionality mode from a Local Control Panel requiring operator intervention. The operation philosophy is below:
After selecting the Auto or Manual modes, the two energy sources, i.e. Solar and LPG will be available to the operator to choose from, for cooking application. The operator can choose any combination of the above sources. In addition, Process Off and Emergency Shut Down options will also be provided.
1. Solar:- LPG and Thermal storage get by passed by valve combination as per PID and solar field goes to Auto Track mode
2. LPG Heater:- The valve combination changes as per PID and the heater starts firing to raise the temperature to set point of the STCS
For each of the above energy sources, the following variables will be made available:

  • Maintenance Condition- if equipment is physically available
  • Functional Availability- if equipment is functionally available (reasons thereof, if not)
  • User Selection- On/Off in STCS circuit
  • Current Status- Operating condition of the selected equipment

Based on selection of the above by the user, all the following conditions can be activated:

  • Cooking By Solar
  • Cooking By LPG
  • Cooking From Solar and LPG
  • Etc.

In addition, the user will have the option to indicate "No Cooking" and "Heat to be given to water for use in kitchen", "STCS Off" and "Emergency Shut Down" conditions.
As an example, the following example/draft HMI screen indicates maintenance status, functional availability, user selection option and current status for each energy source
PROTECTIONS: All safeties and protection conditions for safe operation of the overall STCS will be active all times not limited to the following:
Solar Defocus and Burner off under following conditions:
Outlet and inlet temperatures high
Stack temperature high
Low flow indicated by DPS
Low level indicated by LS
Low gas pressure
Pump or combustion blower off, Flame Failure etc.

Or

 

 

DETAILED TECHNICAL SPECIFICATIONS OF VARIOUS COMPONENTS OF SOLAR COOKING SYSTEMS (SCHEFFLER DISHES)

The solar steam/pressurized hot water/oil generating system will comprise of automatically tracked parabolic concentrators and balance of system (BOS) for conditioning and utilizing thermal energy in working fluid. The working fluid can be in the form of water, steam and organic or inorganic fluid. BOS may consist of solar thermal receivers, steam/ hot water/oil pipelines, feed water/oil pumps, tank assemblies, steel structures and civil works, instrumentation like pressure gauges and temperature indicators etc. It will be hooked up with conventional system already in use for specific applications. In case of new systems, fossil fuel based boiler, vessels for cooking/ vapour absorption machine for cooling etc may be provided as the case may be. Minimum technical specifications of various components of the system will be as per below:

Concentrators

Shape & make of each

Of any shape made of reflecting mirror(s) fixed to a

concentrator

supporting frame / structure

Aperture area

10 sq. m minimum (for Scheffler dishes, it will be p/ 4 x

 

 

lengths of major & minor axis of the ellipse)

Reflecting mirrors

 

i)

Material*

i) High quality glass mirrors for outdoor use with

 

 

protective layers of coating on back surface and sides

 

 

to protect from exterior weathering effect or any other

 

 

reflecting material of similar reflectivity and durability.

 

 

For coastal and colder regions, special protections to

 

 

be made.

ii)

Reflectivity

ii) 90% minimum with a maximum degradation of 10%

 

 

over its life span. Warranty/ guaranty to be provided

 

 

for a period of five years. To be replaced immediately

 

 

by the supplier if found deteriorating during this period.

iii)

Mirror fixing

iii) With positive locking or sticking by industry proven

 

 

outdoor-rated adhesives. Due protection of mirror

 

 

coatings be taken while fixing the mirrors. Tying of

 

 

mirrors with wires not acceptable. For high wind areas

 

 

special protection to be made.

 

 

* For newer upcoming technologies, reflectors other than

 

 

glass mirrors will also be acceptable subject to fulfillment

 

 

of all the above requirements

 

 

Concentration ratio

Over 80 for single axis and 120 for double axis tracking

(Aperture/ Receiver areas)

concentrators

 

 

Tracking Arrangement

 

· Any reliable automatic tracking mechanism with motorized reverse in evening & park at morning position including safe position in case of abnormal operating conditions.

· Made of standard components; to be protected from rain, dust & outside environment

· Tracking accuracy : +/- 0.5 degree (to be ensured using field-calibrated inclinometer)

 

Heat receivers, Headers and piping

  • Tested working fluid pressure: 1.5 times of designed pressure
  • Receivers : Of boiler/standard industry quality to sustain required temperature and pressure
  • Header material and piping : Designed & manufactured as per IBR/ standard industry quality

Insulation

  • All working fluid piping to be insulated with minimum thickness of 50 mm of PUF or rock wool. Headers or water-steam tank, insulated sides of receiver etc. to have minimum insulation of 75 mm. For colder regions facing sub zero temperatures, minimum thickness will be 100 mm and 150 mm respectively. In such regions cold water pipe lines including valves etc. will also be insulated. Insulation on receivers should withstand a minimum temperature of 600c.
  • All insulated components to have Al sheet or powder coated steel sheet cladding as per industrial practices so as not to allow rain water to sip in the insulation.

 

Frames & supporting structure

  • Strong enough to avoid any deformation of the reflector dish during manhandling/ tracking/under wind pressure of 200 km per hour
  • Of mild steel/ any other strong material with epoxy/anti-rust coating


Instrumentation & Controls

  • Complete with all instrumentation such as pressure gauge, temperature indicator, fluid level indicators, safety valves, fluid meter etc. Data acquisition and control system with online monitoring to be installed for automatic monitoring, control and record of all important process parameters in installations above 500 sq. m. of dish area.

Other requirements

  • Systems with Scheffler dishes having single axis automatic tracking arrangement will not be installed with more than 30 dishes at a place. For bigger systems, the dishes have to be of two axis automatic tracking mechanism.
  • All parts/components will be of weather resistant design/specifications to withstand natural weathering outdoors under local climatic conditions, for a minimum period of 15 years. Warranty for a minimum period of 5 years will be provided by the supplier. Necessary spares will also be provided so that the user do not face any problem atleast during the warranty period.
  • The steel structures provided to support various components of the system will be fabricated in such a way that they are able to take load (both wind load and static dead load) of the whole system. In case the terrace where the system is to be installed is not strong enough to bear the loads, these should be transferred into columns and beams and the proposed load arrangement must be discussed with the concerned civil engineering department and their approval obtained.
  • The personnel of the buyer/user institution will be trained by the supplier in the operation and maintenance of the system and its back-up system. Proper manuals will be prepared and provided to the user. Log book will also be supplied to the and user so that proper documentation is maintained.
  • The other important features of system will be i) it will have easy access to the user and proper walkway and platforms will be supplied for easy operation and maintenance of the system wherever necessary ii) safety features such as safety valves etc will be incorporated in the system so that system does not explode under pressure and iii) proper instrumentation as mentioned above will be provided so that user could see the status of system and take precautions /corrective steps if the system does not behave as expected.

 

 

Note: General

  • Any improvements in the above specifications of all types of solar concentrating systems, leading to cost reduction and/ or and higher efficiency of the system will be acceptable.
  • The manufacturer/ supplier will provide the details of his system in the proposal with schematic diagram showing each and every component, its working procedure, tracking arrangement, technical specifications with quantum and size of various components and other highlights, if any alongwith a test report of his dish from one of the Test Centers of MNRE.

Or

 

 

TECHNICAL SPECIFICATION

For Supply, erection and commissioning of Concentrating Solar Thermal (CST) based Solar Steam system for Steam Cooking Application with Thermal Storage Facility.

PART – A SUPPLY

 

1.0. FUNCTIONAL REQUIREMENT

The Solar Concentrator along with thermal storage system will be used to generate steam directly at a required pressure of 6 to 8 bar from the solar radiation and used for the Steam Cooking Application at canteen kitchen. The technology is of CST based either Parabolic

  • Paraboloid concentrator with moving receiver type and tracking is of dual axis automatic type.

This specification covers the design, fabrication, and testing the performance of Solar Dish along with its all accessories including reflector and receiver assembly, steam separator / accumulator, feed water pump, dish cleaning system and other necessary accessories. The specification comply with MNRE guidelines.

2.0 Design, Construction and Erection:-

The design, material, construction, manufacture inspection and performance testing of Solar Dish and receiver assembly shall comply with all currently applicable statutes, regulations and safety codes in the locality where the equipment will be installed. Nothing in these specifications shall be construed to relieve the vendor of this responsibility. The equipment supplied comply with the latest applicable Indian standards. Other national standards are acceptable if they are established to be equal or superior to the Indian standards.

3.0 Design Requirements:-

Concentrated Solar Thermal Steam Generation System It should be envisaged for full load operation to cook for a total of 200 - 250 students per day for Breakfast, Lunch andDinner preparation along with thermal storage facility for non-solar hour operation From one or more number of concentrators as per capacity. However, the plant should facilitate for part load operation with one or more Solar Dishes based on cooking energy demand.

  • Tracking mechanism: solar dish shall have automated two axis tracking system to follow the sun throughout a day. solar tracker shall follow the natural trajectory of sun at particular longitude and latitude of the site. Tracker shall have feedback system to take corrective measures for accurate tracking of Sun.

 

 

  • Reflector: The reflective surface of solar concentrators shall use coating of silver deposited on low iron content glass. The reflector shall be of solar grade with reflectivity of more than 90%.
  • Receiver: Receiver for Solar Dish shall be made of steel for efficient heat transfer. The system shall be hydro tested as per IS and steam blown before taking in service.
  • Structure of Dish:
    • Structure for Solar Dish & Receiver mounting and their Tracking System shall be made of Mild Steel. MS components shall be provided with either with galvanization or epoxy paint
    • All structural fasteners shall be GI as per the specification mentioned elsewhere in document.
    • Grade of concrete for all structure shall be M25 or better

 

4.0 Technical Specifications of Various Components of Concentrated Solar Steam Generator

  • Concentrator

 

 

  • Technology
  • Tracking
  • Output
  • Max pressure
  • Steam Generation

Capacity Required

  • Shape & make of each Concentrator
  • Aperture Area Required
  • Maximum Operating wind speed
  • Survival wind speed
  • Foot print required
  • Control System

  • CST Parabolic / Paraboloid concentrator with moving receiver
  • Point focus - Dual Axis Tracking Solar Dish.
  • Saturated Steam @ 6 - 8 Bar.
  • 10 Bar.

 

To generate solar steam energy required to cook for 200 -250 students in a day for Breakfast, Lunch & Dinner preparation along with thermal storage facility for non-solar hour operation from one or more number of concentrators.

    • Parabolic/ Paraboloid Solar Concentrator with a point focus, made up of solar grade high efficiency mirrors fixed on a Supporting structure. The concentrator shall be automated two axis tracking with automatic return to parking
    • minimum 25 M2 and above per dish
    • 10 m/s or 36 Km/ Hr.
    • 47 m/s or 170 Km/ Hr.
    • minimum space to be occupied by the dishes for the installation on the ROOF TOP / GROUND The site feasibility to be studied by the vendors before submitting the final quote.
  • Micro controller/PLC based control system which shall include

Suitable devices for sensing solar radiation, position of the dish, wind

 

speed, receiver status etc. The input of the

Devices shall be used as feedback for high accuracy tracking in

both axis (seasonal and diurnal) for positioning the dish with

± 0.2 deg accuracy. and for safe operation of the plant.

  • Reflecting Mirrors:
    • Material: High reflectivity solar grade flat float low iron mirrors for outdoor applications with protective layers of coating to protect from exterior weathering effect or any other reflecting material of similar reflectivity and durability.
    • Reflectivity: 90% minimum with a maximum degradation of 10% over its life span. Warranty should be provided for a period of five years. Any deterioration found within the warranty period, the mirrors should be replaced free of cost immediately.
    • Mirror fixing: The mirrors should be fixed with positive locking,due protection to the mirror coatings be taken while fixing the mirrors.
  • Receiver & Thermal Storage: a). Heat Receiver -

· The receiver shall directly generate steam at the required pressure.
· The receiver shall be cavity absorber type.
· The receiver shall be designed to with stand 10 bar pressure.

· The Standard should meet Std. - ANSI:B - 31.1 (or) ASME Sec 8, Div. II

b). Pressurized Hot water / Steam storage tank:

· The storage tank should comply with standards ASME Sec 8, Div II.

· The suitable storage facility to be provided to meet the STEAM requirement of non-solar hours cooking operation at each different Hostel.

· The real time energy generated is considered for preparation of Lunch and Dinner and offline/stored energy is considered for breakfast preparation ie., from the thermal storage facility.

  • Pumps :-

· The pumps used in the system should comply with the following standards:-
· API: 674/5: Reciprocating pumps
· IS: 1520 - Horizontal centrifugal umps
· IS : 5659 - Pumps for process water

  • Piping – Std. - ANSI : B - 31.1 :

Steam / Hot water piping shall be of SA 106 Grade with fittings of SA 105, 3000# for sizes less than 40 NB.

  • Solar Dish Cleaning System :-

It shall be a complete unit including high-pressure-jet pump, hose, pipe, nozzle, lance etc

  • Insulation:

All working fluid piping shall be insulated with mineral wool of density of 120kg/m³. All insulated components shall have Aluminum sheet cladding with 26SWG thickness as per industrial practices.

  • Frames & supporting structure:

Strong enough to avoid any deformation of the dish under wind speed of 200 km per hour when parked. The structure shall be constructed of mild steel / any other strong material and shall be galvanized (min 65 µm) or epoxy coating (with 120-150 DFT). The structure shall be designed for operating life of 25 years.

  • Instrumentation & Controls:

Complete with all instrumentation such as pressure gauges, temperature indicators, fluid level indicators, safety valves, etc.

  • Tracking Arrangement:

Complete reliable automatic dual axis tracking mechanism (Vertical & Horizontal) which will orient towards the sun at the touch of a button and with motorized reverse tracking for parking (safe position) of solar dish in evening & for parking in case of any emergency conditions. No manual intervention shall be required in normal course of operation. However, manual override for all functionality of the dish shall be provided. For seasonal movements also, no manual adjustments shall be required. The tracking shall be made of standard components.

  • Steam Cooking vessels and Back up boiler arrangement:

Suitable capacity steam cooking vessels and LPG based back up boiler needs to be provided

    • Non jacketed vessels for steam cooking : vessle made out of 18swg 304 quality with lid , saftey value , bottom drane value mounted on SS pipe stand with manual tilting arrangement.
    • Jacketed vessels with insulation for steam cooking vessel : vessle made out of 18swg 304 quality with lid , saftey value , bottom drane value mounted on SS pipe stand with manual tilting arrangement.
  • Other requirements:
  • All parts/components will be of weather resistant, design/ specifications to withstand natural weathering outdoors under local climatic conditions.
  • Warranty for a minimum period of 5 years shall be provided for reflective mirrors.
  • The foundations and steel structures shall be designed and constructed / fabricated strictly in compliance with IS 456 and IS 800 respectively with specific consideration for wind load as specified elsewhere in this specification.
  • The personnel of the buyer/ user institution will be trained by the supplier in the operation and maintenance of the system and its back up system. Proper manuals will be prepared and provided to the user.
  • The other important features of the system should include :-
    • It shall have easy access to the user and proper walkway and platforms should be supplied for easy operation and maintenance of the reflectors wherever necessary.
    • Safety features such as safety valves for pressure safety, temperature sensors for temperature safety, wind sensor for structural safety etc should be incorporated in the system.
    • Proper instrumentation as mentioned above should be provided so that the user could see the status of the system and take precautions/Corrective steps if the system does not behave as expected.
    • Proper provision shall be made for cleaning of the mirrors

 

 

Cost and economics of the technology

Solar Thermal technology (cooking system) cost and economics depend on many variables such as location, no of people, food items , cooking timings , site orientation, distance of installation technology ( i.e.Thermic fluid & steam based) & system configuration( i.e. Parabolic tarf type, Scheffler , Single axis tracking / double axis tracking etc).
Thus ,cost and economics can not be identified precisely before preparing feasibility report .

 

 

Benefits of the technology

Economics

  • The energy that comes from the sun is free and inexhaustible. Without the need to buy fuel – whether it is gas, electricity, charcoal, wood, or dung — there is more money left in the purse to purchase other necessities. The choice shouldn’t be food or fuel.

Environmental

  • We are all dependent on the earth’s limited resources of fossil fuels. And the dwindling forests are being depleted for firewood. Cooking with the sun reduces the dependence on these resources.

Burning wood, charcoal, fossil fuels, and other types of fuel contribute to the ever increasing global air pollution. Because there is no fire and no flames, there is no air pollution. Because there is no fire and no flame, solar cookers can be used in “no burn” areas and on “no burn” days. So it is perfect for camping in areas with fire restrictions.
Because solar cookers use the sun and you use less fuel, there is less garbage to deal with. There are fewer bottles of butane to carry to a campsite, and fewer bottles to carry out of a campsite. And, of course, fewer empty butane bottles in the landfill. Large solar ovens have been built on top of Mt. Everest for this same reason – fewer bottles of fuel to carry up and down the mountain. Solavore Sport Solar Oven benefits of solar cooking
Health

  • The use of solar cooking not only reduces air pollution outside, it reduces air pollution inside as well. Smoke from cooking fires irritates and injures the lungs and eyes. With fewer open cooking fires and less smoke, the health of women and children around the globe is improved.

Whether it be in a village hut or on a suburban patio, open cooking fires and hot barbeque grills present a danger to everyone, but especially to children. Using a solar oven, with no open flames, prevents burns and is safe for children to play around.

  • Solar thermal indirect cooking improves cleanliness and hygiene in kitchen.
  • In Rigveda, Shradul Muni reveals the benefits of solar food as quoted. Sun cooked food improves cellular health and longevity. It strengthens health and mind and removes three major physical disorder (Tridosh) related to digestion, blood circulation and respiratory system. It protects from all deceases. Sun cooked food has great medicinal value. It enhance intellect, genius. Researchers at School of Medicine, New York also confirm that solar cooked food do not release AGEs (Advanced Glycation End Products) which are associated with Heart disease, Diabetes and Cancer.

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  • Solar ovens can be used to sterilize dishes and medical equipment.

Cooking

  • Solar cookers can bake, boil, steam, or roast. Most solar cookers reach and maintain temperatures between 250 degrees and 350 degrees, plenty hot enough to cook. Parabolic cookers reach extremely high temperatures that can fry and grill. Keeping the heat adjusted only requires keeping the cooker focused into the sun.
  • Parabolic Solar Cooks faster than other types of solar cookers- The very high temperatures produced result in faster cooking as compared to other solar cooking technologies.
  • Solar cooking generally requires less water to cook because the water does not boil away taking valuable nutrients with it.
  • In Solar Oven,Food cooks slowly and the cooking times are very variable and forgiving. Most food does not burn in a solar cooker. Food cooked longer tends to become more tender and moist and flavorful. Foods with a high sugar content such as cookies will eventually burn, but even that has a long flexible cooking window .Parabolic Solar Cooker benefits of solar cooking.
  • High-performance parabolic solar cookers can attain temperatures above 290 °C (550 °F). They can be used to grill meats, stir-fry vegetables, make soup, bake bread, and boil water in minutes. Vacuum tube type cookers can heat up even in the clouds and freezing cold.

Self – sufficiency

  • In times of power outages due to storms / blackouts / unavailability of fuels, a solar cooker allows one to cook a meal and feed people.

Last Modified on : 2019-06-03