Showing posts with label Suitable. Show all posts
Showing posts with label Suitable. Show all posts

Suitable Material For Tubing And Piping Engineering Essay

The metallurgy of tubing is a very important factor while choosing tubing for a particular environment. Generally the tubing is made up of carbon or low alloy steels, martensitic stainless steel, Duplex stainless steel or other corrosion resistant alloys like Nickel-base alloy etc.

METALLURGY FOR TUBING

Carbon steel is an alloy of carbon and iron containing up to 2% carbon and up to 1.65% manganese and residual quantities of other elements.Steels with a total alloying element content of less than about 5% but more than specified for carbon steel are designated as low alloy steel.Carbon steel is the most common alloy used in oil industry because of its relatively low cost.

Though corrosion resistance of these steels is limited still they have been used in oil industry since long satisfactorily. They are suitable for mildly corrosive environments like low partial pressure of CO2 & low partial pressure of H2S.

A material selected for a particular environment may not remain suitable in the case the environmental conditions change.CO2 can cause extreme weight loss corrosion & localized corrosion, H2S can cause sulphide stress cracking and corrosion. Chlorides at high temperature can cause stress corrosion cracking and pitting of metals, while low pH in general increases corrosion rate.

For example the following material are considered to be resistant to sulphide stress cracking :

Low and medium alloy carbon, containing less than 1% nickel.

AISI 300 series stainless steels (Austenitic) that is fully annealed and free of cold work.

The following materials have been found to have little or no resistance to sulphide stress cracking:

AISI Grades 420 and 13% Cr martensitic stainless steel.

All cold finished steels including low and medium alloy steels, many variety of stainless steel.

The limitations of Carbon steel, 9-Cr-1 Mo, 13-Cr, Duplex stainless steel are encountered in various environments and downhole operations.

METALLURGY OPTIONS FOR TUBING

The various metallurgical options examined for tubing and other downhole equipment are Carbon & Low Alloy Steels, 9 Cr-1Mo steel, 13% Cr stainless steel, Duplex Stainless steel and nickel based alloys.

A brief of the suitability and limitations of these materials in various environments encountered in oil and gas wells:

9Cr-1Mo steel

This steel is immune to stress corrosion cracking in the presence of chlorides like other nickel free low alloy steels.

Corrosion resistance of this steel in the presence of H2S is poor. Hence it is not used in tubing metallurgy commonly.

13Cr Stainless steel

This steel can be used upto 100 atms CO2 partial pressure and upto 150 degree Celsius temperature with chloride upto 50 gms/L.

This martensitic grade is known to be susceptible to sulphide stress cracking in sour environment.This material is generally used for sweet wells where minimum souring is expected.

Duplex Stainless Steel

Duplex SS has excellent corrosion resistance in CO2 environment.

The limitation of their usage is their susceptibility to stress corrosion cracking at high temperature and limited resistance to sulphide stress cracking, when H2S is present in the produced fluid.

Nickel Based Alloys

Nickel based alloys are required to be used in extremely corrosive conditions involving very high partial pressure of H2S and CO2 along with presence of free sulphur or oxygen.

SELECTION OF TUBING METALLURGY

From the various metallurgical options I have analyzed, it can be concluded that low alloy carbon steel is not suitable for the wells where high corrosion risk involved, particularly in offshore. If low allow materials were to be used, an intensive corrosion inhibitor treatment program is essential. However, even with the best of programs, the solution to the problem would be trial and error.

Although 9Cr-1 Mo steels are resistant to CO2 attack, they should not be considered for this application since their application in chloride environment is limited up to 10 gms/l (1%).With the high concentrations of chlorides coupled with the high well bore temperature; this material is not suitable for downhole use in these wells.

Duplex stainless steel is susceptible to chloride stress cracking and should not be used with the CaCl2 packer fluid. Also, the price for Duplex material is three to four times the cost of 13 Cr SS material, which would make it economically unacceptable.

Hence, in spite of the additional up-front cost for tubing , it is recommended that based on the caliper survey results , high corrosion risk wells of field should be re-completed with 13% Cr SS L-80 tubing material.

PROBLEMS OBSERVED

The occurrence of metal loss corrosion in pipeline is caused by the presence of corrodents in the produced water. Internal corrosion in pipeline can be caused by the presence of mill scale, slag inclusions, improper heat treatment, improper welding, too high or too low velocity etc. The erosion/corrosion effect can be caused by too high fluid velocity. Water and sludge build develop with too low fluid velocity that may cause pitting and bacteria infestations. At low fluid velocity, water will tend to segregate to the bottom of the pipeline. Once the pipeline is water wetted, the corrosion begins. When corrosion is not controlled, time to first failure due to corrosion will be normally from three to twelve years depending on the wall thickness and operating conditions.

Corrosion of most material is inevitable and can seldom be completely eliminated. But it can be controlled by carefully selecting material and protection methods at the design stage. For example, as carbon steel is less resistance to corrosion allowance is given in addition to the design thickness when they are expected to handle moderately corrosive fluid. Similarly, external surface of the pipeline are protected from corrosive soils by providing protective coatings. Still, there is always unexpected failure which results from one or more of the following reasons :

Poor choice of material

Defective fabrication

Improper design

Inadequate protection/maintenance

Defective material

CONCLUSION

Corrosion due to presence of CO2 gas along with unfavorable water chemistry is the cause of the piping failures.

It is recommended that tubing metallurgy shall be of L-80 13 Cr stainless steel with premium joints.

The downhole metallurgy shall be 13 Cr SS.

Elastomeric material like shall be used for downhole and well head equipment.

These elastomeric materials include:

Nitrile: A rubber compound with base material as Butadiene Acrylonitrile.

Viton : A fluoroelastomer manufactured by Dupont.

Fluorel :A fluoroelastomer manufactured by 3M company.

Ryton : A polyphenylene sulfide manufactured by Philips Petroleum Company.



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Suitable For Harnessing Solar Energy Engineering Essay

 


There are several projects like photovoltaic cell in solar panels, solar power concentrator and parabolic dishes devised to harness solar energy in India. These plans prove very fruitful in south eastern parts of India in Tamil Nadu, Karnataka, northern plains in Uttar Pradesh, Bihar, western part of India in Rajasthan and parts of Gujarat. In short, those places which have annual average temperature of more than 25°C are suitable for utilizing this energy into usable power.


In this project we have tried to put up a new way of converting electrical energy directly into mechanical energy without any use of solar cell or mirrors. The idea is supposed to be simple as there is no involvement of dedicated machinery or setup and practically no running cost.


The basic idea lies in the structure and way of using solar energy. In this project, the aim is to convert solar energy into kinetic energy of wind and then use this wind for purposes like rotation of turbine or for any other mechanical work. The basic principle involved is that the heated air is lighter than the cold air. If air gets heated near the surface of earth, then it tries to move up into atmosphere and replace the position of cold air from surrounding. The heated air which moves up, acquires a kinetic energy while moving and can be used to rotate the blades of turbines, if stroked with pressure.


The structure consists of a metallic dish made up of aluminium in which the distance between two diametrically opposite points is 20 meters which has a hole in its centre and is placed on supports such that its outer boundary lies at a distance of 3 meters from ground level. Eight rods made of iron are used as a support, which are inserted in the ground. A frustum shaped pipe with a nozzle at the upper end and lower diameter of 1 meter is used to impart the hot air up to the blades of turbine and a iron pipe of lower diameter 1 meter and length of about 10-15 meters is used to hold this nozzle and turbine. The dish must be designed in such a way that its centre lies 1 meters high from its outer boundary, that is, it forms the shape of a big umbrella roof as shown in figure.


WORKING:


This structure helps us to direct all heated wind toward the centre of the dish and no air is escaped from the outer boundary of dish. The heated air when passed through the centre of dish, tries to move through the thin pipe which further has a nozzle at the end. So the escaping wind moves like a high speed stream in that pipe just like steam as it passes in the thermal power plant, strikes the blade of the turbine which is just in front of nozzle and transfers its momentum and ultimately the blade moves and the next blade comes in place of previous one. Due to the continuous flow of hot air, the turbine starts rotating and hence the connected shaft also starts delivering mechanical output. The cold air moves inside from the bottom of dish and take the place of hot air, gets heated and moves up and thus the cycle continues, and we get mechanical power in the form of rotating shaft of turbine which can be used either to generate electricity, which is our main requirement or in other forms as well, where we need mechanical power, like in pumps or other mechanical machines.


The main difference in this solar power set up and other plants utilizing the same energy is that here we get mechanical energy as the outcome and we can use it in numerous ways but in other projects, like in solar panels and rotating dish we get electrical energy only, this is quite an advantageous part of this project. The other advantage of this project is that we can use the hot air produced through this installation for various other plants and industrial applications like, in drying operation in chemical industries, heat exchangers and preheating of water in thermal power plants and at domestic level it can be used for room heating, driers and water heating which will greatly reduce the domestic power consumption as power consumption in water heating accounts for about 30% of electricity bill and thus this heated gas helps to minimize the electric consumption.


The problem lies in the efficiency of the turbine used, that is, nowadays the turbines manufactured are good for higher speed stream wind but in our model we need a better and lighter turbine which rotates with greater r.p.m with the given speed of wind. As the power output and mechanical work, both depend upon the r.p.m of the rotating shaft so it should be high and for increasing the r.p.m there must be an improvement in our present technology, in the sector of turbine design and material science for improving the quality of materials used for turbine design. The existing industry products require a minimum wind speed of 25 km/hr for production of 10 MW of power, thus we have to improve our technology to reduce this speed.


The other possible disadvantage of this project which is common for most of the solar plants is that, it will not work at night or in rainy seasons. As there will be lesser chances of availability of sun in those periods, hence less heated air production and consequently reduction in movement of air, so power production would get a pause for this period. The idea of storage of energy in rechargeable batteries might prove useful for those periods. There must be regular supervision and checking of the dish to prevent the development of holes and cracks in it, as it would greatly reduce the efficiency of the system by leaking the air. The overall performance would also be greatly affected.


COST, INVESTMENT AND RETURN:


Surface Area of Dish can be calculated as:


(X + 1)2 = 102 + X2


(X2 + 1 +2.X) = 100 + X2


2X = 99


X = 49.5 m


Hence, Radius = 50.5 m


Sin? = (10/50.5)


? = Sin-1(10/50.5)


? = 11.42o


Hence, the ends of the dish make an angle of (2 x 11.42) = 22.84o


Therefore, the Surface area of dish = (?/360) x 4p x (Radius)2


= (22.84/360) x 4 x (22/7) x (50.5)2


= 2034 m2


Since, Thickness of dish =3mm


Therefore, Volume of dish =2034 X.003=6.102 m3


Surface area of circular pipe = p X Diameter of pipe X Height of pipe


=3.14 X 1 X 10m


=31.4 m2


Thickness of Pipe = .005 m


Volume of material used in pipe= 31.4 X .005=0.157 m3


The cost analysis is done by discrete method, that is, by quantizing various costs as follows:


a) Cost of dish= (area of dish) X (thickness of plate) X (Density of metal) X cost of metal per kilogram = 2034m2 X .003 m X 2700kg/m3 X Rs130/kg = Rs 2142000


b) Cost of eight supports= 8 X 3 m X cost per meter of support= 24 X 3 m X Rs 150/m =Rs 10800


c) Cost of pipe= (curved surface area of pipe) X cost of sheet = 31.4 m2 X Rs 200/m2 = Rs 6280


d) Cost of nozzle and frustum = Rs 10000


e) Cost of turbine, blades and shaft= Rs 0.5 million


f) Labour charge= Rs 3 million


g) Maintenance cost and land rent= Rs 1 million


h) Miscellaneous charge= Rs 2-2.5 million rupees


TOTAL expected cost = Rs8.6 million


RETURN ANALYSIS:


In Indian scenario we have almost 300 clear sunny days and on an average 10 hours of bright sunlight available so we can calculate the power output in kilowatt hour as


300 X 10 X 60 X 60 X 10 MW/3.6 X 106


=3 x107 KWh of power


Expected sales rate = Rs 2 per unit


Total expected annual return = Rs 60 million


Expected annual profit: Rs 51 million


After analysing the cost and return, it is found that this project remains profitable over the year and gives a profitable return in the summer season.


EFFECT OF GOVERNMENT INCENTIVES:


The Government of India has a very positive and supportive approach towards the solar power. It provides manufacturers and users of commercial and near commercial technologies, with ‘soft’ loans on favourable terms through the IREDA (Indian Renewable Energy Development Agency). The RBI (Reserve Bank of India) terms the renewable energy industry as “Priority Sector”, and has permitted Indian Companies to accept investment under the ‘automatic route’ without obtaining prior approval from RBI.


The Govt of India also provides exemptions/concessions in the excise tax duty on the manufacture of the solar energy systems and devices such as flat plate solar collectors, solar water heater and systems and any specially designed devices which operate those systems. Their incentives include concession on custom duty, 10 year tax holidays and sales and electricity tax exemption and preferential tariffs. It also includes capital subsidies.


The financial assistance of the Central Government is one of the factors which are highly helpful in the solar power market. It provides up to Rs 50 lakhs per city for a period of 5 years, Rs 20 lakhs for awareness generation, capacity building and other promotional activities, Rs 10 lakhs for preparation of a master plan, setting up institutional arrangements, oversight of implementation during the period of 5 years respectively.


The State Electricity Regulatory Commission has been mandated to source up to 10% of their power from renewable energy sources.


The Government based incentives also provide INR 0.5/ KWh of power sold, for independent power producers with capacity >5MW, for the projects that don’t claim accelerated depreciation benefits.


The State Government has set a remunerative price under power purchase policy for the power generated through solar energy system, fed to the grid by private sector. It also has provisions and policy packages including banking, third party sale and buy-back of solar energy power. The State Government also encourages NGO’s and small entrepreneurs for their participation in solar power market.


In a nutshell, the Indian government provides its support to a larger extent for the development of a sustainable solar power market.


SOLAR POWER MARKET:


India has seen only modest pace of growth , relative to demand , in solar power generation. This has resulted in persistent supply shortages for both urban and rural customers. The main customers of solar power generation market include homeowners, businesses and utility companies.


The demand for electricity in developing countries is growing at a fast pace. The potential worldwide market for solar power over the next 20 years is estimated at 600 GW or 6000 plants of 100 MW solar capacities, most of this in developing countries like India.


Over the next 20 years, It is predicted that there will be actual installations of 45 GW or over twenty 100 MW solar capacity plants per year, assuming niche markets could allow for a 7.5% penetration rate. The actual penetration rate will depend on progress in reducing the cost/performance ratio, support from governments (and the GEF), and energy prices.


The above graph represents the daily utility load profiles for four developing countries: India, Jordan, Egypt and Mexico. The values for India are the average of three regions. After analyzing the above graph, one can forecast that the solar power has a great future in developing countries; hence this plan can be promising for India as it has its maximum consumption in day time so we can rely on this type of setups for our energy needs.


In 2008, the cumulative Solar power capacity was 15 GW. Growth in recent years has been 15% per year. There are estimated 40 million households (2.5% of the total) which were using solar power worldwide in 2004.


China is the leader; 10% of Chinese households use solar power; the target for 2020 being 30%.


In 2008, 65.6% of existing global solar power capacity was in China; followed by European Union (12.3%), Turkey (5.8%), Japan (4.1%) and Israel (2.8%). The Indian share was 1.2%.


The estimated break up of solar power installations in India (till 2009) is as follows:


Residential (80%)


2.108


Hotels (6%)


0.158


Hospitals (3%)


0.079


Industry (6%)


0.158


Other (Railway + Defence + Hostel + Religious places,


other) (5%)


0.132


2.635


The main factors contributing the demand rise in recent years are


• Growth in new urban housing; rising disposable income; increased propensity for consumer durables


• Arrival of ETC & improvements in supply chain


• Energy price hike


• Policy initiatives


According to a survey, five states will lead demand-expansion, as is evident from the following table:


Karnataka


3.72


0.16


3.88


Maharashtra


3.5


0.31


3.80


Tamil Nadu


1.53


0.14


1.67


Andhra Pradesh


1.08


0.09


1.17


Gujarat


0.9


0.06


0.96


%age of 5 states


67.1%


Analysis of demand at the district level shows that a large part of the demand would come from selected urbanized districts. Some of the key districts (out of the 29 surveyed districts) which have large potential for solar power generation market are Bangalore, Pune, NCR, Thane, Hydrabad, Nagpur, Kolkata, Chennai, Coimbatore, Ahmadabad and Jaipur. Among them, Bangalore has highest solar power potential of about 1.94 million m2, in 2022.


Solar power market development plan:


The solar power market development plan is divided into 3 phases:


1. Niche Market Awareness:


The main objectives are to rekindle interest in Solar power generation in India, allow the industry to start-up production processes, determine the current cost and performance of Solar power generation ,and evaluate new Solar power generation concepts to see if they have promise for long term commercialization.


The main activity is to increase market awareness by funding one or two Solar plants in


India. These plants will likely be smaller than the optimum of over 200 MW because of the need to minimize investor risk and to start-up production processes.


It is recommended that the initial market focus should be in those markets where the conditions for solar power generation are currently most promising. Previous experience shows that these conditions are High Solar Resource, High fossil fuel prices, Daytime Peaking Utility, Inefficient Conventional Power Plants, Access to Water and the Grid.


Depending on the cost of power displaced, the financial support to achieve cost parity will range from $400 to $750 million or $550 to $1000 per kW.


2. Market Expansion:


The purpose of the market expansion phase is to develop larger systems to benefit from economies of scale, continue with product development to improve performance and lower costs, create a market large enough that manufacturers can justify construction of production lines, and standardize system designs. A standard design will help to improve the system cost performance by reducing design costs, streamlining equipment procurement and minimizing construction and start-up problems.


In this phase, 3000 MW of additional solar capacity is installed, or fifteen 200 MW plants. The cost of solar power is expected to fall from over 10 cents/kWh to between 7 and 8 cents per kWh.


Depending on the cost of power displaced, the financial support to achieve cost parity will range from $0.5 to $1.8 billion or $350 to $600 per kW.


3. Market acceptance:


The final part in the development plan is the market acceptance phase. The goal for this phase is to set up the necessary market structure so that solar power generating plants can compete with conventional power plants without financial support from the GEF or others.


The investment requirement in this phase is the most difficult to estimate and subject to the


widest variation. The cost of solar generated electricity is expected to fall close to conventional power values. A small difference in solar costs can have a huge impact on the market penetration.


Solar power generation market has the ability to dramatically transform lives. In a country, where 450 million people live without access to electricity and have to depend on kerosene and other alternatives for whatever little lighting they can get at night, solar power as an application in small home lightening system lightens up their lives.



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