Lesson 3 - Steam Theory SAQ
This lesson allows you to test yourself on the material covered in the Steam Theory lesson and determine the level to which you have met the learning outcomes.
Self-Assessment Questions
1. *
a) Describe what the following terms mean in relation to steam:
(i) Saturated liquid
(ii) Saturated vapour
(iii) Superheated vapour
b) Rank the terms below in order of smallest to largest specific enthalpy:
(i) Saturated liquid
(ii) Saturated vapour
(iii) Superheated vapour
c) What type of steam is used in a brewery? Explain why.
2. ** Using the Mollier diagram in the figure below, answer the following questions.
a) What is the enthalpy of dry saturated steam at 200°C?
b) What is the pressure of the steam mentioned in question a)?
c) The steam is condensed isobarically to a wetness fraction of 0.7, what is the enthalpy now?
d) What is the temperature of the steam from question c)?
Figure: Mollier diagram for water
3. *
a) What is the difference between culinary and utility steam?
b) In which places within a brewery might you find culinary steam?
c) In which places within a brewery might you find utility steam?
4. ** Using the steam table below, answer the following questions.
a) Steam is available in your brewery at 1.5 MPa (1.4 MPa g). What steam flow rate is required to increase the temperature of 1,000 kg of wort from 77°C to 100°C in 25 min? The specific heat capacity of wort is 4,050 J kg-1 K-1.
b) How much steam would be required if the pressure of the steam was increased to 2.5 MPa (2.4 MPa g)?
Table: Steam table
|
Temperature °C
|
Pressure MPa
|
Specific Volume m3 kg-1 |
Specific Enthalpy Liquid kJ kg-1 |
Specific Enthalpy of Vaporisation kJ kg-1 |
Specific Enthalpy Vapour kJ kg-1 |
|
0.01 |
0.000612 |
205.9912 |
0 |
2,500.92 |
2,500.92 |
|
5 |
0.000873 |
147.0113 |
21.02 |
2,489.04 |
2,510.06 |
|
10 |
0.001228 |
106.3 |
42.02 |
2,477.19 |
2,519.21 |
|
30 |
0.004247 |
32.8783 |
125.73 |
2,429.82 |
2,555.55 |
|
50 |
0.012400 |
12.0269 |
209.34 |
2,381.95 |
2,591.29 |
|
70 |
0.031200 |
5.0395 |
293.07 |
2,333.03 |
2,626.10 |
|
90 |
0.070200 |
2.3591 |
377.04 |
2,282.49 |
2,659.53 |
|
100 |
0.101400 |
1.6718 |
419.17 |
2,256.40 |
2,675.57 |
|
125 |
0.232200 |
0.7700 |
525.07 |
2,188.03 |
2,713.10 |
|
150 |
0.476200 |
0.3925 |
632.18 |
2,113.75 |
2,745.93 |
|
179.88 |
1 |
0.1944 |
762.52 |
2,014.59 |
2,777.11 |
|
200 |
1.55490 |
0.1272 |
852.27 |
1,939.74 |
2,792.01 |
|
225 |
2.54970 |
0.0784 |
966.80 |
1,835.35 |
2,802.15 |
|
263.94 |
5 |
0.0394 |
1,154.64 |
1,639.57 |
2,794.21 |
|
280 |
6.41660 |
0.0302 |
1,236.88 |
1,542.99 |
2,779.87 |
|
285.83 |
7 |
0.0274 |
1,267.66 |
1,504.97 |
2,772.63 |
|
295.01 |
8 |
0.0235 |
1,317.31 |
1,441.37 |
2,758.68 |
|
311.00 |
10 |
0.0180 |
1,408.06 |
1,317.43 |
2,725.49 |