THERMO DYNAMIC Essay Example

Thermo Dynamic

The compressor cycles takes in gas, air or vapor mainly at low pressures and through the process of compression, it turns it to high pressure. The compressor has been considered a high power consumption machine for the mechanical conversions to occur effectively. The compressed air or vapor can be used to operate many plants including a steam or gas turbine plant among others. Compressors are mainly identified as either reciprocating or rotary compressors. The report deals with the reciprocating compressors where both have positive displacement. The reciprocating compressor occur in either single, or multi stage or single and double acting compressors. The report considers the reciprocating compressors generally. The operation of the compressors requires the application of some standards that ensure the safety of developing, and operating the machines while identifying possible hazards related to the compressors.

The steam and gas turbine operate highly on the Rankine Cycle principle. The steam and gas operations depend on the first and second law of thermodynamics also besides many others. However, the Rankine Cycle as presented in the report analysis section is the main factor that determines the operations of the gas and steam turbines. The main components of the rankine cycle are he feed pump, compressor, boiler and turbine as will be presented in the report. The efficiency guarantee of these components determines the power in and out efficiency. The report focuses more on steam power plants rather than the gas turbine operations.

Functioning of Steam power plant through circuit and property diagrams

1. Introduction

The report begin by providing a report analysis that deals directly on the details of compressor cycles, their faults and hazards. It also thorough and in detail presents the operating principles of steam and gas turbines through the Rankine Cycle. More importantly, it uses the Rankine Cycle Property diagrams and graphs to illustrate the steam power plant operations. The report then provides a discussion that explains all the information of the compressor and steam power plant cycles and their operations before presenting a conclusions on their operations.

1. Report and analysis tasks

The clearance volume effect is perceived in the compressor through improving the efficiency of the volumetric factor. It ensures the volume is not high or low but perfect as it should be. The clearance volume also increases the machinery efficiency. The volumetric efficiency is given as the ratio of mass density and the air-fuel mixture of the air compressor cylinder. Therefore, it is the ratio where the fluid volume gets displaced by the plunger or the piston from the swept volume.

The isothermal efficiency is the work input ration compared against the isothermal process. That is; the ratio of the work input compared to the real time processes that are occurring between the inlet and the exit pressures occurring at the same time. The isothermal presents the work input divided by the real work of the compressor. The isothermal efficiency of the compressor is affected by an increase in the discharge pressure.

The pressure ratio is perceived when the pressure discharge increases; it is the reciprocating compressor ratio. The pressure ratio affects the isothermal efficiency by improving the results that lead to a decrease in the isothermal efficiency. That is; as pressure ratio increases, the isothermal efficiency decreases (Patil, et al., 2015). Similarly, the pressure ratio increases the clearance volume, which reduces the volumetric efficiency.

The importance of cooling during compression since the pressure is kept constant, which increases the volumetric efficiency, and the temperatures are also kept low ensuring the products are not compromised. An intercooler is used for the cooling process, which is important as it removes the existing heat that exists between the stages of the compressors.

Safety Risks

Reciprocating air compressors safety risks occur in issues such as the fittings, hoses and piping processes. To ensure safety some factors as this should be regularly checked to ensure the pressure working the compressor gives efficiency of the volumetric and isothermal processes among others.

The air supply throughout the compressor should be attained and identified at the operation point, while the hoses should be grease free to ensure deterioration of the components is low, including the safety of using the compressor in the future. More importantly, the hose ought to strung effectively to avoiding the personnel from falling or tripping. Thus, to ensure safety of those using the product, the hose should be suspended overhead. They should also be secured, which would eliminate the possibility of whipping if accidents were to occur.

Thus, safety measures should be maintained through

• Air receivers been regularly investigated

• The air distribution lines ought to be inspected regularly also to ensure secure connections are done among others.

• The devices for pressure regulation should be regularly inspected and maintained including gauges, valves and air tank safety among many others.

• Rapture of the compressor is also a safety issue that ought to be attained through ensuring the excessive pressure is managed to ensure the inside pressure does not lead to the exploding of the compressor machine. Therefore, managing and regularly checking the pressure of the machine is needed to ensure the machine does not explode.

• The machine may also be having possible oil leaks that threaten the safety of the operation of the machine and the area or plant the machine is at. Oil leaks may lead to large explosions that are a adanger to everyone in the working area

• Overheating of some parts of the compressor could also cause danger to the people operating the machine among others since overheating of the compressor could also lead to an explosion while igniting other devices that may lead to higher fires.

Faults are caused by issues such as

• When the outlets are blocked and the flow is restricted

• The automatic controls may fail to guarantee low consumption of air

• The compressor may malfunction leading to problems such as over speeding or low speed affecting the end product.

• The compressor may overheat and lead to the storing of carbonaceous deposits that may leads to issues such as explosions or fires.

T ask 6

STEAM

J I

A = Turbine W Turbine C = Condenser B =Feed Pump D = Boiler

E = Alternator F = Furnace G = Dust collector H = Pulveriser

I = Cool Hopper J = Chimney

The Rankine Cycle presents the process of steam heating engines. The feed pump will experience compression while the turbine experiences the expansion, though these reactions are not isentropic. The process increases the feed pump power required and lowers the turbine power that is produced.

Based on the Rankine cycle, liquid will go through the boiler from the feed pump, which is then heated to the temperature anticipated. The vapour attained, is then expanded into the turbine, which leads to the work process. Therefore, the vapour and liquid attained from the turbine are condensed at the condenser at a low pressure, while cooling the water. The n the condensed water pressure is fed into the feed pump.

Based on the above Rankine Cycle, the following details are given:

Boiler = 100 Bar

Condenser Pressure = 0.07 bar

Steam temperature leaving the boiler = 400 ^oc

Mass flow =55 kg/s

Enthalpy Values = (

Dryness fraction

The Rankine Cycle based on these factors deals with just four factors, the feed pump, boiler, condenser and turbine. The Rankine cycle presented above can be explained as:

The steam leaves the boiler at 100 bar and enters the turbine, which is expanded to the 400 ^oC, then enters the condenser at 0.7 bar. The steam gets heated again from the condenser at 0.7 Bar through the turbine second stage at, and the process repeats itself.

h2 = 3097 kJ/kg at 100 bar and 400 ^oC

hf = 163 kJ/kg

h fg = 2409 kJ/ kg

The isentropic expansion is given as

S2 = 6.213 kJ/ kg

K = S3 = 0.559 + 8.13x

h3 = hf + x hfg = 163 + 0.733 (2409) = 1928.8 kJ/Kg

Condenser

h4 = hf at 0.7 bar = 163kJ/kg

Steam out = m (h3 – h4) = 55 (1928 -163) = 97. 1MW

Given that the input power of the pump is displaced, h4 = h1 = 163kJ/kg

ɵ in = h2 – h1 = 3102 kJ/ kg

3097kJ/kg – 163 kJ/kg = 2924kJ/kg

The ultimate input of power is given through the energy flow changes given in (mv (Δp)

Power in = 55 (0.001) (100 bar – 0.7 bar) * 10⁵ = 550Kw

Therefore, the power in = m (h1 – h4)

55 (h1 – 163 kJ/kg)

H1 = 173 kJ/kg

Efficiency

P (Output) = h2 –h3 = 1189.4 kJ/kg

P (output) = 3097 -1928 = 1169kJ/kg

n = p / ɵ in = — %

n = 1169 kJ/kg / 2924 kJ/kg = 0.4%

Entropy T – S diagram

The figure above presents the Rankine cycle on the temperature and entropy process. The figure presents constant pressure curve on the lower left to the upper right. The constant pressure is the isobaric process that happens in the boiler and turbine. The isentropic process occurs when there is no entropy change, which is a vertical line on the diagram, which depicts the amount of heat transferred to the gas.

1. Discussion

Compressors operate through taking in enough fluid to ensure the pressure is increased, where the reciprocating compressors are highly applied in high pressure applications. The efficiency of the reciprocating compressors is related to volumetric and isothermal efficiency. The reciprocating compressor is therefore identified as a positive displacement machine that compresses gas and releases it at the highest pressure (Kehlhofer, et al., 2009). During the development, operation and maintenance of the compressors, the adequacy, safety and maintenance practices should be considered to ensure the faults and possible hazards that the machine may encounter are managed. The reciprocating compressors mainly compress air, gas and vapour.

The working and operational principle of a steam power plant is dependent on the Rankine cycle process. The Rankine Cycle operates through four main components. The turbine, boiler, pump and condenser. Water is pumped at the low from the condenser pressures, which is then thrusted in high pressures into the boiler. The water at this point is converted into steam at a constant pressure (Isobaric process) where heat is added to the boiler constantly (Sotirios & Andreas, 2008).

The steam is then expanded into the turbine where through the constant pressure, the heat in the condenser, the steam is converted into water again. During the process of operating the boiler, it is superheated leading to the steam production as one can perceive on the entropy T-S diagram, which should increase the effluent quality increase of the turbine. Thus, the Rankine cycle thermal efficiency is increased to improve the boiler effluent. The Rankine cycle is presented in the T-S and P-V graphs. Entropy presents the properties that determine the energy usefulness, which is given by heat transfer, temperature and entropy. Thus kJ/kg as given in the equations before depicts the entropy units.

1. Conclusion

The report presents that the reciprocating compressors are positive displacement machines that compress low pressure air or vapor to high pressure. The performance of the compressor is highly dependent on the piston displacement, clearance volume, which determines the volumetric efficiency and the isothermal efficiency. That is; the ensure that when converting the low pressure fluids to compressed air, the right pressure is applied not high or low but appropriate. The steam power plant operations are based on the working principle of the Rankine Cycle. The Rankine cycle uses water mainly for the cycle though other fluids can be used. It begins by presenting the water or any other liquid in the isentropic compression process then it is compressed and driven in the boiler where heat is constantly added to develop the saturated vapor that is then expanded to the turbine in the isentropic process leading to the last process of condensation as the fluid goes back to the first state.

References

Kehlhofer, R., Frank, H., Bert, R. & Franz, S., 2009. Combined-cycle gas & steam turbine power plants. New York: Pennwell Books.

Patil, P. V., Jadhav, S. S. & Dhas, D. N., 2015. Performance and Analysis of Single Stage Reciprocating Air Compressor Test Rig. SSRG: International Journal of Mechanical Engineeing, 2(5), pp. 56-64.

Sotirios, K. & Andreas, S., 2008. Supercritical Fluid Parameters in Organic Rankine Cycle Applications. International Journal of Thermodynamics, 11(3), pp. 101 — 108.