1. A level control system comprising:
a plurality of sensors configured to measure a plurality of parameters related to a drum, wherein the plurality of parameters comprise a drum liquid level, a vapor flow rate leaving the drum, a downstream pressure of the drum, and a feed-liquid flow rate entering the drum; and
a level controller configured to adjust a level control valve in accordance with a signal representative of the drum liquid level, a signal representative of the downstream pressure and a signal representative of a given drum liquid level set point,
wherein the level controller is configured to receive a feedback signal representative of a combination of a fraction of the signal representative of the drum liquid level and a fraction of the signal representative of the downstream pressure.
2. The system of claim 1, wherein the signal representative of the drum liquid level is at a low frequency derived from one of the plurality of sensors measuring the drum liquid level within the drum.
3. The system of claim 2, wherein the level controller is configured to pass the signal representative of the drum liquid level through a low pass filter.
4. The system of claim 3, wherein the level controller is further configured to add a gain to the signal representative of the drum liquid level after being passed through the low pass filter.
5. The system of claim 1, wherein the signal representative of the downstream pressure is at a high frequency derived from one of the plurality of sensors measuring the downstream pressure of the drum.
6. The system of claim 5, wherein the level controller is configured to pass the signal representative of the downstream pressure through a high pass filter.
7. The system of claim 6, wherein the level controller is further configured to add a gain to the signal representative of the downstream pressure after being passed through the high pass filter.
8. The system of claim 1, wherein the level controller comprises a cascaded Proportional Integral (PI) flow control for controlling the level control valve.
9. A level control system for controlling a liquid level in a drum containing a two-phase fluid, the system comprising:
a plurality of sensors configured to measure a plurality of parameters related to the drum, wherein the plurality of parameters comprise a drum liquid level, a vapor flow rate leaving the drum, a downstream pressure of the drum, and a feed-liquid flow rate entering the drum; and
a level controller configured to modify a liquid level set point of the drum based on output signals at high frequency measured from one of the plurality of sensors, wherein the level controller is configured to change a liquid level in the drum based on the modified liquid level set point by manipulating one or more control elements coupled to the drum.
10. The system of claim 9, wherein the level controller is configured to pass the output signals at high frequency through a high pass filter.
11. The system of claim 10, wherein the level controller is further configured to add a gain to the output signals at high frequency after being passed through the high pass filter.
12. The system of claim 9, wherein the output signals at high frequency comprises of superheater pressure signals or drum pressure signals or pressure signals in downcomer tubes of evaporator.
13. The system of claim 9, wherein the one or more control elements comprises a pressure control valve, blow down valve, feed-water control valve, or combinations thereof coupled to the boiler drum.
14. A method for controlling a liquid level in a drum containing a two-phase fluid, the method comprising:
obtaining a plurality of sensing parameters related to the drum via a plurality of sensors; wherein sensing parameters comprises sensing drum liquid level, vapor flow rate leaving the drum, pressure in the drum, downstream pressure, and feed-liquid flow rate entering the drum indicative of a state of the drum;
receiving a feedback signal by a level controller, wherein the feedback signal is representative of a combination of a fraction of a signal representative of the drum liquid level at low frequency and a fraction of a signal representative of the downstream pressure at high frequency,
adjusting a level control valve in accordance with the feedback signal, a signal representative of the vapor flow rate leaving the drum, a signal representative of the feed-liquid flow rate entering the drum and a signal representative of a given drum level set point, and
controlling the drum liquid level at the given drum level set point.
15. The method of claim 14, further comprising passing the signal representative of the drum liquid level at low frequency through a low pass filter and further adding a gain.
16. The method of claim 15, further comprising passing the signal representative of the downstream pressure at high frequency through a high pass filter and further adding a gain.
17. The method of claim 14, further comprising modifying a liquid level set point of the drum based on output signals representative of the downstream pressure at high frequency measured from one of the plurality of sensors.
18. The method of claim 17, further comprising controlling the liquid level in the drum based on the modified liquid level set point by manipulating one or more control elements coupled to the drum.
19. The method of claim 18, wherein manipulating the one or more control elements coupled to the drum is performed manually, automatically, or combinations thereof.
20. The method of claim 18, wherein the one or more control elements includes a pressure control valve, blow down valve, feed-water control valve, or combinations thereof coupled to the boiler drum.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A dual polarization antenna comprising:
a reflection plate; and
a radiation module comprising first to fourth radiation devices comprising first to fourth radiation arms having bending parts, respectively,
wherein the bending parts of the first to fourth radiation arms are sequentially adjacent to each other and are symmetrical to each other in four directions to form a shape when viewed from the top, the first to fourth radiation devices have supports integrally extending toward the reflection plate at the bending parts of the first to fourth radiation arms, and the radiation module comprises a first feeding line installed to transfer signals to the first and third radiation arms and a second feeding line installed to transfer signals to the second and fourth radiation arms, and
wherein the first and second feeding lines are strip lines, the first feeding line transfers a signal through non-contact coupling with the first radiation arm, and the second feeding line transfers a signal through non-contact coupling with the second radiation arm.
2. The dual polarization antenna of claim 1, wherein the first feeding line extends to the support of the third radiation device facing in a slant line direction via the bending part of the first radiation arm along the support of the first radiation device, and the second feeding line extends to the support of the fourth radiation device facing in a slant line direction along the bending part of the second radiation arm along the support of the second radiation device.
3. The dual polarization antenna of claim 2, wherein a plurality of spacers for supporting the feeding lines and maintaining intervals of the supports to be constant are formed between the first and second feeding lines and the supports of the first to fourth radiation devices, and a spacer for preventing a contact between the two feeding lines is further formed at a site where the first and second feeding lines cross each other.
4. The dual polarization antenna of claim 1, wherein the first feeding line is connected to the third radiation arm of the third radiation device facing in a slant line direction via the bending part of the first radiation arm along the support of the first radiation device, and the second feeding line is connected to the fourth radiation arm of the fourth radiation device facing in a slant line direction via the bending part of the second radiation arm along the support of the second radiation device.
5. The dual polarization antenna of claim 1, wherein the first to fourth radiation arms of the first to fourth radiation devices are configured such that a width of a surface of a radiation device facing another radiation device is larger than a surface of the radiation device from which signals are radiated.
6. The dual polarization antenna of claim 1, wherein a bending angle of the bending parts of the first to fourth radiation arms is a right angle.
7. The dual polarization antenna of claim 1, wherein lengths of the supports of the first to fourth radiation devices are designed based on a wavelength of a processed signal to be opened.
8. A multiple band antenna system comprising:
a reflection plate;
a first radiation module comprising first to fourth radiation devices comprising first to fourth radiation arms having bending parts, respectively, wherein the first to fourth radiation arms are disposed on the reflection plate such that the bending parts sequentially adjacent to each other and form a shape when viewed from the top; and
a second or third radiation module installed on the reflection plate at at least one of upper and lower sides of left and right sides of the installation site of the first radiation module having the shape,
wherein the first to fourth radiation devices comprise supports integrally extending from the bending part of the first to fourth radiation arms toward the reflection plate, and the first radiation module comprises a first feeding line installed to transmit signals to the first and third radiation arms and a second feeding line installed to transmit signals to the second and fourth radiation arms, and,
wherein the first and second feeding lines are strip lines, and the first feeding line transfers a signal through non-contact coupling with the first radiation arm, and the second feeding line transfers a signal through non-contact coupling with the second radiation arm.
9. The multiple band antenna system of claim 8, wherein the second or third radiation module is installed such that the installation site of the second or third radiation module at least partially overlap empty spaces at upper and lower portions of left and right sides of the first radiation module having the shape.
10. The multiple band antenna of claim 8, wherein the first feeding line extends to the support of the third radiation device facing in a slant line direction via the bending part of the first radiation arm along the support of the first radiation device, and the second feeding line extends to the support of the fourth radiation device facing in a slant line direction along the bending part of the second radiation arm along the support of the second radiation device.
11. The multiple band antenna of claim 10, wherein a plurality of spacers for supporting the feeding lines and maintaining intervals of the supports to be constant are formed between the first and second feeding lines and the supports of the first to fourth radiation devices, and a spacer for preventing a contact between the two feeding lines is further formed at a site where the first and second feeding lines cross each other.
12. The multiple band antenna of claim 8, wherein the first feeding line is connected to the third radiation arm of the third radiation device facing in a slant line direction via the bending part of the first radiation arm along the support of the first radiation device, and the second feeding line is connected to the fourth radiation arm of the fourth radiation device facing in a slant line direction via the bending part of the second radiation arm along the support of the second radiation device.
13. The multiple band antenna of claim 8, wherein the first to fourth radiation arms of the first to fourth radiation devices are configured such that a width of a surface of a radiation device facing another radiation device is larger than a surface of the radiation device from which signals are radiated.
14. The multiple band antenna of claim 8, wherein a bending angle of the bending parts of the first to fourth radiation arms is a right angle.
15. The multiple band antenna of claim 8, wherein lengths of the supports of the first to fourth radiation devices are designed based on a wavelength of a processed signal to be opened.