Once-through steam generator

Patent metadata

Field	Value
Publication number	US-9574766-B2
Application number	US-201414909585-A
Country	US
Kind code	B2
Filing date	Jul 29, 2014
Priority date	Aug 6, 2013
Publication date	Feb 21, 2017
Grant date	Feb 21, 2017

Abstract

A once-through steam generator includes a combustion chamber, the walls of which comprise vertically arranged evaporator pipes connected to one another in gas-tight fashion by pipe webs, through which evaporator pipes flows a flow medium from bottom to top. The evaporator pipes are combined by upstream inlet collectors to form more intensely and less intensely heated pipe groups. A feed water supply is assigned to respective inlet collectors. At least one regulating valve regulates throttling of the mass flow of the flow medium into the evaporator pipes. To determine a control variable for the regulating valve, temperature measurement device measures outlet temperatures of the flow medium exiting the evaporator pipes. Each of the more intensely and less intensely heated pipe groups is assigned to one of the inlet collectors and to an outlet collector, and each of the outlet collectors has one of the temperature measurement devices.

First claim

The invention claimed is:

1. A once-through steam generator, comprising:
a burning chamber of substantially rectangular cross section, the burning chamber walls of which comprise substantially vertically arranged evaporator tubes of the once-through steam generator which are connected to one another in a gastight manner via tube webs and are flowed through by a flow medium from the bottom to the top,
wherein the evaporator tubes of the burning chamber walls are combined in accordance with their degree of heating by inlet headers which are arranged upstream in each case to form more heated tube groups and less heated tube groups, and wherein the respective inlet headers are assigned a feed water supply,
at least one control valve provided in the region of the feed water supply for the controlled throttling of the mass flow of the flow medium in the evaporator tubes,
temperature measuring devices for measuring outlet temperatures of the flow medium from the evaporator tubes located in the region of outlet headers which are arranged downstream in order to determine a control variable for the at least one control valve,
wherein each of the more heated tube groups and less heated tube groups are assigned in each case to one of the inlet headers and an outlet header,
wherein each of the outlet headers has one of the temperature measuring devices, and
wherein the less heated tube groups being corner wall regions of the substantially rectangular burning chamber, and wherein each of the four corner wall regions has a dedicated feed water supply line with in each case one control valve, and
a controller configured to reduce the feed water supply of the less heated tube groups by throttling of the at least one control valve to such an extent that outlet temperatures of the more heated tube groups are equalized to those of the less heated tube groups.

2. The once-through steam generator as claimed in claim 1 ,
wherein the more heated tube groups are middle wall regions of the substantially rectangular burning chamber, and each of the four middle wall regions has a dedicated feed water supply with in each case one control valve.

3. The once-through steam generator as claimed in claim 1 ;
wherein the controller is further configured to reduce the feed water supply of the more heated tube groups by throttling of the at least one control valve to such an extent that the outlet temperatures of the more heated tube groups are equalized to those of the less heated tube groups.

4. The once-through steam generator as claimed in claim 1 ;
wherein the controller is further configured to establish an equalization of the outlet temperatures between the more heated and less heated tube groups.

5. The once-through steam generator as claimed in claim 1 ,
wherein the once-through steam generator comprises a forced-flow steam generator.

6. A method, comprising:
operating a once-through steam generator comprising:
a burning chamber of substantially rectangular cross section, the burning chamber walls of which comprise substantially vertically arranged evaporator tubes of the once-through steam generator which are connected to one another in a gastight manner via tube webs and are flowed through by a flow medium from the bottom to the top, wherein the evaporator tubes of the burning chamber walls are combined in accordance with their degree of heating by inlet headers which are arranged upstream in each case to form more heated tube groups and less heated tube groups, and wherein the respective inlet headers are assigned a feed water supply;
at least one control valve provided in the region of the feed water supply for the controlled throttling of the mass flow of the flow medium in the evaporator tubes; and
temperature measuring devices for measuring outlet temperatures of the flow medium from the evaporator tubes located in the region of outlet headers which are arranged downstream in order to determine a control variable for the at least one control valve;
wherein each of the more heated tube groups and less heated tube groups are assigned in each case to one of the inlet headers and an outlet header,
wherein each of the outlet headers has one of the temperature measuring devices, and
wherein the less heated tube groups being corner wall regions of the substantially rectangular burning chamber, and wherein each of the four corner wall regions has a dedicated feed water supply line with in each case one control valve; and

reducing the feed water supply of the less heated tube groups by throttling of the at least one control valve to such an extent that outlet temperatures of the more heated tube groups are equalized to those of the less heated tube groups.

7. The method of claim 6 , further comprising:
reducing the feed water supply of the more heated tube groups by throttling of the at least one control valve to such an extent that the outlet temperatures of the more heated tube groups are equalized to those of the less heated tube groups.

8. The method of claim 6 , further comprising:
establishing an equalization of the outlet temperatures between the more heated and less heated tube groups.

9. A once-through steam generator, comprising:
a burning chamber of substantially rectangular cross section and comprising burning chamber walls which comprise substantially vertically arranged evaporator tubes connected to one another in a gastight manner via tube webs and which conduct a flow medium from the bottom to the top of the burning chamber, wherein the evaporator tubes are combined to form more heated tube groups in middle wall regions of the burning chamber and less heated tube groups in corner wall regions of the burning chamber;
a dedicated inlet header and a dedicated outlet header for each tube group;
a dedicated feedwater supply line in fluid communication with each inlet header of the less heated tube groups;
a control valve in the feedwater supply line for controlling a mass flow of the mass flow medium;
a temperature measuring device for measuring outlet temperatures of the flow medium;
a controller in signal communication with the temperature measuring device and the control valve and configured to control the mass flow rate of the flow medium in the dedicated feedwater supply line independent of a mass flow rate of the flow medium in the more heated tube groups in order to homogenize an outlet temperature of the flow medium of the less heated tube groups with an outlet temperature of the flow medium of the more heated tube groups.

10. The once-through steam generator of claim 9 , further comprising:
a dedicated feedwater supply line for each corner region;
a dedicated control valve in each feedwater supply line; and
a dedicated temperature measuring device for each outlet header;
wherein the controller is further configured to control the mass flow rate of the flow medium in each of the corner regions independent of the mass flow rate in other corner regions in order to homogenize an outlet temperature of the flow medium of the corner regions with an outlet temperature of the flow medium of the more heated tube groups.

Assignees

• Siemens Ag

Inventors

• Brodesser Joachim
• Brückner Jan
• Effert Martin
• Schulze Tobias
• Thomas Frank

Classifications

• F22B21/34

  built-up from water tubes grouped in panel form surrounding the combustion chamber, i.e. radiation boilers · CPC title

• F22B29/062 Primary

  involving vertically-disposed water tubes · CPC title

• F22B21/345

  with a tube bundle between an upper and a lower drum in the convection pass · CPC title

• F22B35/10

  of once-through type · CPC title

• F22B35/108

  Control systems for steam generators having multiple flow paths · CPC title