Ball Valve: An Overview - Assignment Example

Name: Course: Instructor’s Name: Institution: Date: Question 1 Valves are the devices that are used to regulate and direct the flow of a fluid such as gases and liquid through opening, closing or partially obstructing several passages. Ball valve is for off or on manages with no pressure drop and ideal for rapid shut-off since a 45 degree turn offers a complete shutoff angle, compared too many turns needed on most manual valves. This valve possesses a spherical disc and the part of the valve that manages the flow through it and this sphere has a hole in the middle so that when the port is in line with both ends of the valve flow would occur. The ball valves are strong and normally work to attain perfect shutoff even after years of disuse therefore they are an excellent choice for shutoff applications and are often preferred to globe and gate valves. The ball valves do not provide the best manage that may be necessary in throttling applications but are sometimes used for this purpose. It can also be used for severe duty, high pressure, high tolerance applications and they are typically made of stainless steel, titanium, satellite, hastelloy, and brass. Advantages of ball valve The media can be used to direct the flow of the two ring road network which means unrestricted flow of medium Form relatively simple manufacturing process is better Relatively short length of the structure Disadvantages of ball valves Normal valve has two sealing surface to processing polishing and maintenance of an increase of some difficulties Opening and closing a long time. Globe valve is a linear motion valve used to start, stop and regulate fluid flow. They are named for their spherical body shape with the two halves of the body being separated by an internal baffle and it has an opening that forms a seat on to which a movable plug can be screwed in to close the valve. Some years ago the global valve had the spherical shape which gave them the name, but the recent global valves do not have much of a spherical shape. Never the less the term global valve is such a mechanism are also often known as stop valve since they do not have the global shape but the term stop valve may refer to valves which are used to stop flow even when they have mechanisms. Global valves are used for applications requiring throttling and frequent operation, for instance, global valves or valves possessing the same mechanism may be used as a sampling valve which, are usually shut except when liquid samples are being taken, and since the baffle restricts flow they are not recommended where full, unobstructed flow is needed. Advantages of using globe valves: Good shutoff capability Reasonably good throttling capability The major drawbacks to the use of a globe valve are: Higher pressure drop compared to a gate valve Large valve sizes require considerable power or a larger actuator to operate Gate valves can be manufactured in wide range of size from 5mm to above 2000mm diameter and this design is well tested and proven. The valve can also be based on a solid wedge which can adjust to suit the seal faces or a parallel faced based on two disc which slide between parallel sealing faces with a mechanism forms forcing the discs out on the last part of the spindle travel. The gate valves are generally used in the process industry for on and off service, the design is not good for throttling duty because the sealing surfaces can easily suffer from wire drawing when low flow are being maintained against high differential pressure and the design give very poor flow control characteristics. Advantages and disadvantages of gate valve Fluid resistance Fully open the sealing surface of the medium by the work of erosion than global valve Disadvantages Opening height dimension and a larger installation space needed is also big In the opening and closing process the sealing surface were relatively frictions, friction loss of big even at high temperature likely to cause abrasion The Bourdon pressure tube gauge uses the principle that a flatten tube tends to change to a more circular cross-section when pressurize. The basic principle of bourdon tube pressure gauge is that when an elastic transducer is subjected to a pressure it defects and this deflection is proportional to the applied pressure when calibrated. The application of Bourdon tube pressure gauge is used to measure medium to very high pressures. Advantages of bourdon tube pressure gauge It gives accurate results Its cost is low the bourdon tube pressure gauge is simple to construct It can be modified to give electrical outputs They are safe even for high pressure measurement Disadvantages They response is slow to changes in pressure They are subjected to hysteresis They are sensitive to shocks and vibrations Amplification is a must as the displacement of the free end of the bourdon tube is slow It cannot be used for precision measurement Liquid and gas flow can be measures in volumetric or mass flow rates for example litres per second or kilograms per second. These measurements can be converted between one another if the material’s density is known and the density for a liquid is almost independent of the liquid condition. In engineering contexts the volumetric flow rate is usually given the symbol Q. A filter is a device that removes particles from a given liquid or gas it includes a disposable medium for removing particles of specified micron sizes whereas a strainer is also a filter but uses a perforated plate or screen mesh to remove large particles from the process stream. The main advantage of a strainer is that it is reusable and has three levels of straining course, medium and fine. The course straining – in this case the strainer SEB is a single course strainer with large perforations suited for straining out large particles and foreign materials. On the other hand the medium and fine straining a strainer SES is available with either a perforated metal basket 0.062 diameter perforations or wire mesh basket suited for staining out particles down to 73 microns. A vessel under pressure means a vessel which operates under pressure and includes a boiler, pressure vessel, pressurized system or portable gas container. The special considerations all users are supposed to apply include the following; The subject to the provisions of sub regulation and no user shall use any vessel under pressure unless it has been designed and constructed in accordance with a health and safety standard incorporated in to these regulations in terms of section 44 of the act. The certificate needed by sub regulation, in the case of a pressure vessel or portable gas container may refer to more than one pressure vessel or portable gas container has the same design pressures and dimension. These considerations are more important for high pressure gases than high pressure liquids because it offers the higher pressure needed to move the mobile phase analyse through the densely packed column. The surge tanks its main function is to match two flows that are not identical in time but are expected to average out over the long run. The main purpose is to maintain sufficient inventory to feed the process and to maintain sufficient void capacity to continue receiving feed as it arrives. The header tank it is a bubble trap. It is used to provide an air bubble free supply of fuel to the engine. It is also used to add a little extra flight time. A hydraulic accumulator is a device in which potential energy is stored in the form of s compressed gas or spring or by a raise weight to be used to exert a force against a relatively incompressible fluid. It is used in fluid power systems to accumulate energy and to smooth out pulsations. Question 2 Ceramic disc valve is used to control the flow rate of moderately abrasive raw products in a food processing. A boiler is a closed vessel in which water or fluid is heated and heated or vaporized fluid exits the boiler for use in various processes or heating. A valve used to prevent boiler water from flowing back to a feed pump when pump is stopped is check valve. The nurpo valve may fit between the check valve and boiler drum. A pressure carburettor is a type of fuel metering system manufactured for piston aircraft engines and was developed to prevent fuel starvation during inverted flight. The valve used to control the fuel flow in a carburettor is servo valve since it controls the rate at which fuel can enter the pressure carburettor. Question 3 Renewable energy is advisable this is because it comes from natural resources such as sunlight wind rain tides and geothermal heat which are renewable or naturally replenished. For home lighting and cooking households will make use of biogas and solar energy. Maintaining a comfortable temperature in buildings and homes can be achieved by planting deciduous trees and plants this have been promoted as a means of controlling solar heating and cooling. When planted on the southern side of a building their leaves provide shade during the summer while the bare limbs allow light to pass during the winter since bare leafless trees shade a third to a half of ancient solar radiation, therefore there is a balance between benefits of summer shading and the corresponding loss of winter heating. For both overseas and overland transportation people should use ethanol for transportation. In Brazil there are no longer, light vehicles running on pure gasoline, for instance at the end of year 2008 there were thirty five thousand filling stations throughout Brazil with at least one ethanol pump. The ethanol fuel program uses modern equipment and cheap sugar cane, therefore it’s cheaper to make. In the case of distance transportation that is commuting and shopping people may use motive power this includes car and boats, but they require to use hydrogen as a potential fuel. Free hydrogen does not occur naturally in quantity and thus it must be generated from some other energy source by steam reformation of natural gas. The use of hydrogen depends on issues of energy sourcing such as fossil fuel use, climate change and sustainable energy generation, thus saving for the public at large. Question 4 The constitution of a fuel is 85% carbon, 13% hydrogen, and 2% oxygen. When burning this fuel is a boiler furnace the air supply is 50% in excess of the stoichiometric, inlet temperature of the air being 31o C and the temperature of exhaust gas in the funnel is 280o C. Calculate: (a) The Energy Content (or the Calorific Value) of the fuel. (b) The mass of air supplied per kg of fuel used. (c) The heat energy carried away by the exhaust gases expressed as a percentage of the heat energy supplied, taking the Cp exhaust gases as 1.005kJ/kgK (a) Calorific Value 85 + (13 - 2)/50 = 1.92 Converting grams to calories 1.92 = 13.8 0 C (b) Actual mass of air supplied/kg of fuel (AAS) = {1 + EA/100} x theoretical air (1 + 50/100) x 13.8 = 20.7 (c) Percentage heat loss m x Cp x (Tf – Ta) x 100 Where m = Mass of dry flue gas in kg/kg of fuel Cp = Specific heat of flue gas in kCal/kg Tf = Flue gas temperature in 0C Ta = Ambient temperature in 0C 20.7 x 1.005 x (280 -31) x 100 = 518007.15 kJ/kgK (5) The cylinder on an engine has a stroke of 300 mm and a bore of 250 mm. The volume ratio of compression is 14:1. Air in the cylinder at the beginning of compression has a pressure of 96 kPa and a temperature of 93o C. The air is compressed for the full stroke according to the law pv1.3 = C. Determine: (a) The mass of air in the cylinder (b) The work transfer (c) The heat transfer (d) The Temperature and pressure at the end of compression. (For air take =1.4 and Cp= 1.006 kJ/kgK) (e) After doing the above calculations briefly state how you expect the mass flow rate of air to be if this was a 4 stroke 6 cylinder engine running at 3000 rpm. What would happen if the air filter was partially choked. If the piston rings were leaking state what you would expect the results of a, b, c, and d above would be. (A) Mair = Pair *V M= (300 * 250) 14/15 * 1/15 = 4666.67 46.7 kj (B) Du = ℓq - ℓw or dw = pdv Where P= pressure D= density V= volume 96-93*46.7 = 140.1 kj/kg0C (C) Heat Transfer q = m(DT)Cp. Where q = heat transferred, DT = the change in temperature and Cp = the specific heat 46.7*93*140 =608468.31 kj (d) The Temperature and pressure at the end of compression 608468.31/ 4666.67 = 130.4oC After doing the above calculations briefly state how you expect the mass flow rate of air to be if this was a 4 stroke 6 cylinder engine running at 3000 rpm The mass flow rate of air will be higher, since the 4 stroke 6 cylinder that runs at 3000 rpm has more energy of pumping the air. What would happen if the air filter was partially choked. The mass flow rate of air will starts decreasing partially and finally comes to rest. If the piston rings were leaking state what you would expect the results of a, b, c, and d above would be. The mass of air in the cylinder will still remain the same The work transfer will decrease as well as the heat transfer. The Temperature and pressure at the end of compression will also decrease partially. Question 6 In a galvanised steel water supply line 100 m long and 50 mm in diameter, water is pumped from a reservoir to storage tank at an elevation 8 m above it. The following fittings are used. 1hindged foot valve with strainer, 3 x 90o standard elbows, 2 gate valves, (open), 20 screwed sockets, 1 sudden exit. The viscosity of water is 1 x 10-6 m2/s (pay attention to the units0 and the density is 1000 kg/m3. Refer to the class handouts for the k values of fittings and the absolute roughness of galvanised steel, and determine: (a) The friction factor for a flow rate of 3 L/s 400 * 270/1000 = 108 (b) Using the above constant friction factor determine the system head equation in terms of velocity. Velocity (m/s) = volume flowrate (m3/s) Cross section area (m2) 100 * 50 * 8 = 40000M3 108 s/h * 22/7 * 1 x 10-6 Velocity = 1357.7 V= 0.14 m/s (b) Using a friction factor as determined in (a), determine the system head and fluid power for flow rates of 0, 1.5, 3, 4.5, and 6 L/s 108 * 0/0.14 = 15.2 kw 108 * 1.5/0.14 = 22.68 kw 108 * 3/0.14 = 45.36 kw 108 * 4.5/0.14 = 7.56 kw 108 * 6/0.14 = 90.72 kw (d) Draw a graph of system head and fluid power against flow rate on one sheet of graph paper, using the values determined in(c (e) If the efficiency of the pump was 65% when the flow rate is 5L/s determine the input power to the pump at this flow rate. 65/5= 13kw (f) If the pipe diameter was 65 mm instead of 50 mm what would be the input power to the pump for the same flow rate and pump efficiency as in (e) 66/100 *65 = 42.9kw Work cited Kinsky, Roger. Thermodynamic Fluid Mechanics An Introduction. New York sage 1995 Read More