CA1168889A - Monitoring the superheated state of steam - Google Patents
Monitoring the superheated state of steamInfo
- Publication number
- CA1168889A CA1168889A CA000397661A CA397661A CA1168889A CA 1168889 A CA1168889 A CA 1168889A CA 000397661 A CA000397661 A CA 000397661A CA 397661 A CA397661 A CA 397661A CA 1168889 A CA1168889 A CA 1168889A
- Authority
- CA
- Canada
- Prior art keywords
- steam
- tube
- superheat
- degree
- pressure
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N25/00—Investigating or analyzing materials by the use of thermal means
- G01N25/56—Investigating or analyzing materials by the use of thermal means by investigating moisture content
- G01N25/58—Investigating or analyzing materials by the use of thermal means by investigating moisture content by measuring changes of properties of the material due to heat, cold or expansion
- G01N25/60—Investigating or analyzing materials by the use of thermal means by investigating moisture content by measuring changes of properties of the material due to heat, cold or expansion for determining the wetness of steam
Landscapes
- Physics & Mathematics (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Measuring Fluid Pressure (AREA)
Abstract
Abstract A temperature measurement-independent process and apparatus for determining the degree of superheat in steam by comparing the saturation pressure corresponding to the superheated steam temperature with the pressure of the steam.
Description
1 3 ~
Monitoring the Superheated State of Steam Background of the Invention This invention concerns a method and apparatus for monitoriny the superheated state of steam.
The use of superheated steam is necessary in many manufac-turing processes and in the generation of energy. In this context, steam is understood to have a temperature above the saturation temperature corresponding to the steam pressure.
The precise monitoring of this condition is desirable, so that the equipment using superheated dry steam will not be damaged by wet steam or entrained water droplets. Thus, for example, in a power plant which is fed with superheated steam produced in a straight tube steam generator with shell-side boiling, of the type described in U.S. 3447509 (Sprague), the absence of superheat can lead to severe damage to the ; 15 turbine valves and the turbine.
There exists the possibility of determining the degree of superheat by comparing the steam temperature in the piping - to the turbine with the saturation temperature of the fluid flowing. However, since it is difficult to determine the exact saturation temperature, this method would lead to inexact results.
Brief Summarv of the Invention _ ` The purpose oE this invention is therefore to provide a reliable and -temperature measurement independent method and apparatus for the simple and direct monitoring of the
Monitoring the Superheated State of Steam Background of the Invention This invention concerns a method and apparatus for monitoriny the superheated state of steam.
The use of superheated steam is necessary in many manufac-turing processes and in the generation of energy. In this context, steam is understood to have a temperature above the saturation temperature corresponding to the steam pressure.
The precise monitoring of this condition is desirable, so that the equipment using superheated dry steam will not be damaged by wet steam or entrained water droplets. Thus, for example, in a power plant which is fed with superheated steam produced in a straight tube steam generator with shell-side boiling, of the type described in U.S. 3447509 (Sprague), the absence of superheat can lead to severe damage to the ; 15 turbine valves and the turbine.
There exists the possibility of determining the degree of superheat by comparing the steam temperature in the piping - to the turbine with the saturation temperature of the fluid flowing. However, since it is difficult to determine the exact saturation temperature, this method would lead to inexact results.
Brief Summarv of the Invention _ ` The purpose oE this invention is therefore to provide a reliable and -temperature measurement independent method and apparatus for the simple and direct monitoring of the
- 2 ~ 1 J 6~
superheated state of steam, with which more precise results are produced.
This problem is solved pursuant to the invention by deter-mining the saturation pressure of water in indirect contact S with the steam, corresponding to the steam -temperature, comparing this saturation pressure with the steam pressure, and using the difference of these pressure values as an index for the degree of superheat of the steam.
By this method and apparatus, the superheated state of the steam is monitored while avoiding an uncertain saturation temperature measurement by means of a simple differential pressure measurement.
In a device for implementing this method, a previously evacuated tube is partially filled with water, and sealed at one end. The sealed end of this tube extends into a steam pipel with the water in the end region extending into the steam piping leaving an empty volume to hold a steam cushion formed at the saturation pressure correspondinq to the steam temperature in the piping. The open end of this tube is connected to the measurement chamber of a differ-ential pressure-measuring transducer. Another tube connected directly to the steam piping opens into a second measurement chamber.
The sealed end of the measurement tube is preferably specially formed to maximize the surface to volume ratio thus promoting a more rapid temperature change of the liquid in the end region of the measurement tube in order to improve the transient time response of the device.
With such a device, the degree of superheat can be monitored reliably, since the comparison of two pressure measurements can be carried out in a simple and direct manner.
Thus, in accordance with one aspect of the present invention there is provided apparatus for determining the degree of - 2a ~ ~ 8~
superheat in steam comprising a first tube partially filled with water ancl closed at one end, the closed end of which extends into a steam pipe containing steam, a water level existing in the closed end above which steam is formed in contact with the water in a previously evacuated space, means to transmit pressure in the first tube to a first measurement chamber, means to transmit pressure in the steam pipe to a second measurement chamber, and means to compare the pressures in the measurement chambers to determine the degree of superheat of the steam in khe pipe.
In accordance with a further aspect of the present invention there is provided a method of monitoring the degree of superheat of steam comprising, determining and measuring the saturation pressure corresponding to the temperature of the steam, determining and measurinq the steam pressure and comparing these pressures to indicate the degree of superheat of the steam.
Brief Description of the Drawing Figure 1 is a schematic representation of the inventive l ~ fi ~
apparatus.
Detailed Description of the Drawing Referring to the drawing, superheated steam 2 flows in pipeline 1 from a steam generator, not shown, to a point of use, also not shown. A tube 5, one end of which is sealed 8, extends into steam piping 1. The other end of tube 5 is connected to a first measurement chamber 3 of a differen-tial pressure-measuring transducer 4. The tube 5 is filled with water to the level 6 after prior evacuation leaving an empty space 7 above the level 6 at the sealed end 8. A second tube 9, communicating with the superheated steam 2 in piping 1, is connected to a second measurement chamber 10 of the differential pressure~measuring transducer 4.
In operation, steam is formed in the sealed end 8 of tube 5 and occupies the space above the water level 6. The heat transfer from the steam 2 to the water in tube 5 extending into steam piping 1 results in the formation of steam in contact with the water at the saturation pressure corres-ponding to the steam temperature in piping 1. This pressureis transmitted to first measurement chamber 3. Since the tube 9 is connected directly to the steam piping 1 it will sense and transmit the steam pressure in piping 1 to second measurement chamber 10. The difference between the saturated pressure corresponding to the steam temperature in piping 1 and the steam pressure in this piping provides information on the degree of superheat of the steam to be monitored.
This data therefore can be used as the basis of control and regulatory functions in the steam generating system.
superheated state of steam, with which more precise results are produced.
This problem is solved pursuant to the invention by deter-mining the saturation pressure of water in indirect contact S with the steam, corresponding to the steam -temperature, comparing this saturation pressure with the steam pressure, and using the difference of these pressure values as an index for the degree of superheat of the steam.
By this method and apparatus, the superheated state of the steam is monitored while avoiding an uncertain saturation temperature measurement by means of a simple differential pressure measurement.
In a device for implementing this method, a previously evacuated tube is partially filled with water, and sealed at one end. The sealed end of this tube extends into a steam pipel with the water in the end region extending into the steam piping leaving an empty volume to hold a steam cushion formed at the saturation pressure correspondinq to the steam temperature in the piping. The open end of this tube is connected to the measurement chamber of a differ-ential pressure-measuring transducer. Another tube connected directly to the steam piping opens into a second measurement chamber.
The sealed end of the measurement tube is preferably specially formed to maximize the surface to volume ratio thus promoting a more rapid temperature change of the liquid in the end region of the measurement tube in order to improve the transient time response of the device.
With such a device, the degree of superheat can be monitored reliably, since the comparison of two pressure measurements can be carried out in a simple and direct manner.
Thus, in accordance with one aspect of the present invention there is provided apparatus for determining the degree of - 2a ~ ~ 8~
superheat in steam comprising a first tube partially filled with water ancl closed at one end, the closed end of which extends into a steam pipe containing steam, a water level existing in the closed end above which steam is formed in contact with the water in a previously evacuated space, means to transmit pressure in the first tube to a first measurement chamber, means to transmit pressure in the steam pipe to a second measurement chamber, and means to compare the pressures in the measurement chambers to determine the degree of superheat of the steam in khe pipe.
In accordance with a further aspect of the present invention there is provided a method of monitoring the degree of superheat of steam comprising, determining and measuring the saturation pressure corresponding to the temperature of the steam, determining and measurinq the steam pressure and comparing these pressures to indicate the degree of superheat of the steam.
Brief Description of the Drawing Figure 1 is a schematic representation of the inventive l ~ fi ~
apparatus.
Detailed Description of the Drawing Referring to the drawing, superheated steam 2 flows in pipeline 1 from a steam generator, not shown, to a point of use, also not shown. A tube 5, one end of which is sealed 8, extends into steam piping 1. The other end of tube 5 is connected to a first measurement chamber 3 of a differen-tial pressure-measuring transducer 4. The tube 5 is filled with water to the level 6 after prior evacuation leaving an empty space 7 above the level 6 at the sealed end 8. A second tube 9, communicating with the superheated steam 2 in piping 1, is connected to a second measurement chamber 10 of the differential pressure~measuring transducer 4.
In operation, steam is formed in the sealed end 8 of tube 5 and occupies the space above the water level 6. The heat transfer from the steam 2 to the water in tube 5 extending into steam piping 1 results in the formation of steam in contact with the water at the saturation pressure corres-ponding to the steam temperature in piping 1. This pressureis transmitted to first measurement chamber 3. Since the tube 9 is connected directly to the steam piping 1 it will sense and transmit the steam pressure in piping 1 to second measurement chamber 10. The difference between the saturated pressure corresponding to the steam temperature in piping 1 and the steam pressure in this piping provides information on the degree of superheat of the steam to be monitored.
This data therefore can be used as the basis of control and regulatory functions in the steam generating system.
Claims (3)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. Apparatus for determining the degree of superheat in steam comprising a first tube partially filled with water and closed at one end, the closed end of which extends into a steam pipe containing steam, a water level existing in the closed end above which steam is formed in contact with the water in a previously evacuated space, means to transmit pressure in the first tube to a first measurement chamber, means to transmit pressure in the steam pipe to a second measurement chamber, and means to compare the pressures in the measurement chambers to determine the degree of superheat of the steam in the pipe.
2. The apparatus of Claim 1 in which the sealed end of the first tube has a maximized surface to volume ratio with respect to the remainder of the first tube.
3. A method of monitoring the degree of superheat of steam comprising, determining and measuring the saturation pressure corresponding to the temperature of the steam, determining and measuring the steam pressure and comparing these pressures to indicate the degree of superheat of the steam.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19813108782 DE3108782C2 (en) | 1981-03-07 | 1981-03-07 | Device for determining the degree of superheating of water vapor |
| DEP3108782.5 | 1981-03-07 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1168889A true CA1168889A (en) | 1984-06-12 |
Family
ID=6126656
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000397661A Expired CA1168889A (en) | 1981-03-07 | 1982-03-05 | Monitoring the superheated state of steam |
Country Status (2)
| Country | Link |
|---|---|
| CA (1) | CA1168889A (en) |
| DE (1) | DE3108782C2 (en) |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1053371A (en) * | 1900-01-01 | |||
| DE192547C (en) * | 1907-02-24 | |||
| DE6600366U (en) * | 1968-10-17 | 1969-01-23 | Gerdts Gustav F Kg | DEVICE FOR INDICATING SUBCOOLING AND / OR OVERHEATING OF STEAM |
-
1981
- 1981-03-07 DE DE19813108782 patent/DE3108782C2/en not_active Expired
-
1982
- 1982-03-05 CA CA000397661A patent/CA1168889A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| DE3108782C2 (en) | 1984-10-25 |
| DE3108782A1 (en) | 1982-09-30 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |