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Q: Thermodynamics - Power Cycle Problem ( No Answer,   1 Comment )
Subject: Thermodynamics - Power Cycle Problem
Category: Science > Physics
Asked by: megahog-ga
List Price: $30.00
Posted: 27 Apr 2006 08:35 PDT
Expires: 03 May 2006 13:53 PDT
Question ID: 723353
Ok, here is the main objective:

Design an accumulator for the following service (i.e. CALCULATE ITS
VOLUME) if no more than 95% of
its volume should be occupied by the liquid at any time.....

And this objective must be achieved under these constraints and in the
context of this information: 

(A STEP-BY-STEP ANALYSIS will be greatly
appreciated and compensated with a generous tip. Let me know how long
you spent on this and I will tip you accordingly depending on how FAST
you can return an answer.)

Steam power plants face fluctuating power demands all the time. Since
power can not be
easily stored, one solution to fluctuations in power demand is to pass
variable amounts of
steam through turbines to match power production to power demand. This means that
either the boiler steam production is varied to match varying steam
demand or alternative
ways are found to manipulate steam supply to turbines to match steam
demand. In this
context, consider the following scenario.

A power plant operates at 700 kPa and it has a boiler with steady steam production
capacity of 6000 kg/s. The average steam demand of the power plant
over the period of
an hour is 6000 kg, but the instantaneous demand fluctuates from 4000
to 10000 kg/h. It
is suggested that fluctuations in steam demand by the turbines can be
accommodated by
taking the following steps:
1. Produce saturated steam in the boiler at a pressure of 1000 kPa and operate the
turbines with an inlet steam pressure of 700 kPa.
2. Add an accumulator between the boiler and the plant. An accumulator is
essentially a tank containing mostly saturated liquid water that
?floats on the line?
between the boiler (pressure 1000 kPa) and the plant (i.e. turbine
operating at inlet
pressure of 700 kPa)
3. Have a pressure control valve between the boiler and the accumulator to regulate
pressure upstream of the accumulator and another pressure control valve between
the accumulator and the turbine to regulate steam pressure downstream of the
The accumulator is to be designed such that
(a) Pressure in the accumulator will fluctuate between 1000 kPa and 700 kPa.
(b) When steam demand will be less than boiler output, steam will flow into the
accumulator and will be largely condensed by liquid residing in the accumulator.
In the process, pressure in the accumulator will increase to values greater than
700 kPa.
(c) When steam demand will be greater than boiler output, water in the accumulator
will vaporize and steam will flow out. In this process, pressure in the
accumulator will decrease to values less than 1000 kPa.

There is no answer at this time.

Subject: Re: Thermodynamics - Power Cycle Problem
From: marcusl-ga on 27 Apr 2006 18:09 PDT
Do your own thermodynamics homework, I did.

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