CN210267183U

CN210267183U - System beneficial to rapidly judging whether high-temperature heating surface of thermal power plant is over-temperature

Info

Publication number: CN210267183U
Application number: CN201920855905.5U
Authority: CN
Inventors: 江鹏威; 朱庆华; 柴伟; 孙国良; 徐宏武; 王新; 周玮
Original assignee: CHN Energy Jianbi Power Plant
Current assignee: CHN Energy Jianbi Power Plant
Priority date: 2019-06-06
Filing date: 2019-06-06
Publication date: 2020-04-07
Anticipated expiration: 2029-06-06

Abstract

The utility model belongs to the technical field of thermal power generation control by temperature change, in particular to be favorable to quick judgement thermal power plant high temperature to receive the system whether overtemperature of face, be equipped with the work unit that receives the face in one or more among the thermal power generation system, independently be connected with the sample pipeline on the collection case of each unit exit or the female pipe, the sample pipeline extends and passes behind the cooling arrangement, installs hydrogen concentration detection device on the sample pipeline, and hydrogen concentration detection device on each sample pipeline is system connection respectively in DCS control system.

Description

System beneficial to rapidly judging whether high-temperature heating surface of thermal power plant is over-temperature

Technical Field

The utility model belongs to the technical field of thermal power generation control by temperature change, in particular to be favorable to the system whether super temperature of quick judgement thermal power plant high temperature heated surface.

Background

China is a coal-fired big country, and with the rapid development of the thermal power generation technology using coal as fuel, the temperature of the heating surface of a boiler is higher and higher, the maximum temperature of steam of a double reheating ultra-supercritical boiler reaches 623 ℃, and in order to reach higher efficiency of a thermal power generator, China is researching a high-temperature boiler steam pipeline resistant to 700 ℃.

When the safety of the heating surface is affected by abnormal changes of the heating surface pipe and the water supply in the running process of the boiler, the safety is firstly shown from the temperature, so that whether the heating surface of the boiler is over-temperature or not is very important to quickly and accurately judge, and the safety running of the boiler is directly related. However, in the operation process of the boiler, because the number of the heating surfaces is large, the area is large, the number of monitoring points is large, and the monitoring of the temperature of the heating surfaces of the boiler by operators cannot be comprehensively and continuously monitored.

The traditional heating surface wall temperature monitoring device is a conventional heat sensor, when the temperature is detected to exceed a DCS set value, an alarm system is triggered, but the heat sensor cannot monitor each point of the heating surface of the boiler, in other words, the wall temperature of the heating surface of the boiler measured by the heat sensor only represents the temperature of a certain point and cannot completely represent the actual wall temperature in the boiler, so that the defects of incomplete detection and signal delay exist. And the wall temperature monitoring system has a severe working environment and extremely high temperature, measuring points are easy to burn out, and the furnace needs to be shut down for maintenance, but the furnace is not shut down in a thermal power plant because of one wall temperature monitoring point, so that the burnt out measuring points become monitoring blind points, and great hidden danger is brought to the safe operation of the boiler.

SUMMERY OF THE UTILITY MODEL

In order to solve the technical problem, the utility model provides a system which is beneficial to rapidly judging whether the high temperature heating surface of the thermal power plant is over-temperature, comprising a water wall, a first-level superheater, a last-level superheater, a first-level reheater, a last-level reheater and the like, wherein units of the heating surface are arranged in the water wall, a collection box or a main pipe at the outlet of each unit in which the heating surface is arranged is independently connected with a sampling pipeline, each sampling pipeline extends through a cooling device respectively, each sampling pipeline is provided with a hydrogen concentration detection device respectively for detecting the hydrogen concentration in the sampling pipeline, each hydrogen concentration detection device is respectively and systematically connected with a DCS control system (the DCS control system is provided with a set of alarm system which is independently and systematically connected with each path of hydrogen concentration detection device,

part of water or steam (gasified water, the same applies below) output from the outlets of the units is cooled by cooling equipment through a sampling pipeline connected with a header or a main pipe at the outlet of the unit, and then flows through a hydrogen concentration detection device arranged on the sampling pipeline,

the hydrogen concentration detection device comprises a hydrogen concentration detector.

The steam parameters of modern high-parameter and large-capacity boilers are all above subcritical, water vapor shows strong oxidizing property to metal under the high-temperature condition, water molecules and other metal elements such as iron elements perform oxidation-reduction reaction, namely steam oxidation, and the steam oxidation reaction equation of the metal in the high-temperature and high-pressure water vapor environment is as follows: xM + yH₂O→MxOy+yH₂Modern high-parameter and high-capacity boiler pipes are made of alloy steel, the metal contains metals such as Cr and the like, and the reaction between a boiler heating surface and high-temperature and high-pressure water vapor can be represented by the following chemical equation:

4H₂O+3Fe→Fe₃O₄+4H₂

Fe+2Cr+4H₂O→FeCr₂O₄+4H₂

therefore, the heating surface of the boiler can be oxidized by high-temperature and high-pressure steam to generate hydrogen, the hydrogen is dissolved in water or mixed with steam,

according to a related theory, the oxidation rate of high-temperature steam on a heated surface and the temperature form a certain linear relation, the higher the temperature is, the higher the oxidation rate is, the higher the hydrogen content in the steam is, when the temperature is stable, the reaction rate is certain, the content of dissolved hydrogen in water or steam is stable, and the content of dissolved hydrogen in high-temperature water or high-temperature steam can be very sensitively and quickly reflected on the channel temperature, so that whether the heated surface of the boiler is over-temperature or the heat load is abnormally fluctuated can be judged by monitoring the peak value change of the hydrogen content of the steam in each section of the heated surface of the boiler.

The scheme firstly cools the sample by the sampling pipeline and then passes through the hydrogen concentration detector, thus on one hand, the hydrogen concentration detector is prevented from being damaged by high-temperature steam, on the other hand, the steam with different parameters (the steam temperature of the heating surfaces in different working units is not consistent) is cooled into the same parameter, the uniformity and the accuracy of measurement are convenient,

after cooling, high-temperature water vapor is converted into liquid water, and the amount of generated hydrogen is very small, so that the hydrogen is dissolved in the liquid water formed by cooling, and the concentration of the hydrogen in a sampling pipeline is detected by using an Orbisphere 510 dissolved hydrogen analyzer (the measurement range is 0-500 mug/L, and the measurement precision is 0.1 mug/L) of HACH company in the patent;

preferably, the method comprises the following steps: the traditional wall temperature monitoring system for detecting the temperature of the heating surface in the working unit, namely a conventional heat sensor, is respectively arranged on each working unit, the conventional heat sensor comprises a temperature measuring probe and a display which are used for contacting with the heating surface,

the hydrogen concentration detection device can objectively and accurately reflect whether the heating surface is really over-temperature or not, the problem of incomplete detection is avoided, but the hydrogen concentration detection device cannot give a specific temperature value, and the specific temperature value of a monitoring point on the heating surface can be directly obtained through a conventional heat sensor, in the scheme, the conventional heat sensor is matched with the hydrogen concentration detection device for use, so that once the hydrogen concentration detection device drives an alarm to give an alarm, an operator can obtain the specific temperature value through observing the conventional heat sensor at the moment, and can timely adjust the parameters or operation of the thermal power generation equipment according to the specific temperature value exceeding the upper limit temperature,

although the temperature of the contact point of the temperature measuring probe and the heating surface is displayed by the conventional heat sensor, the alarm is driven by the hydrogen concentration detection device to give an alarm, which shows that the whole heating surface is over-temperature, so that the temperature accuracy displayed by the conventional heat sensor is relatively high.

In practical application, the temperature of a certain section of heating surface is firstly adjusted to be close to the upper limit, the hydrogen data detected by the hydrogen concentration detection device at the moment is recorded, the data is used as an alarm value, and in the practical operation process, once the DCS receives the data sent by the hydrogen concentration detection device and exceeds the alarm value, a corresponding alarm is sent.

By the scheme, whether the heating surface of the boiler is over-temperature or not can be quickly judged, and a blind area which cannot be detected by a traditional wall temperature monitor is monitored, so that operating personnel can quickly and correctly process the blind area, and the overtemperature tube explosion of the heating surface is prevented; the whole detection investment cost is low, the occupied area is small, the installation is convenient, the reliability and the stability are realized, the heating condition and the heat load of each heating surface of the boiler can be monitored in a segmented mode, the system is suitable for a wall temperature monitoring system of the heating surface of the boiler of a thermal power plant, and is particularly suitable for a modern high-parameter and high-capacity supercritical (supercritical) boiler, the high-temperature oxidation condition of the heating surface of the boiler can be monitored, the growth period of an oxide skin is slowed down, and the overhaul period and the chemical cleaning period of the boiler are prolonged.

Drawings

FIG. 1 is a schematic diagram of the system of the present invention for rapidly determining whether the high temperature heating surface of the thermal power plant is over-temperature,

the system comprises a working unit 1, a water-cooled wall 11, a primary superheater 12, a final superheater 13, a primary reheater 14, a final reheater 15, a sampling pipeline 2, a cooling device 3, a hydrogen concentration detection device (hydrogen concentration detector) 4, a DCS control system 5, a conventional heat sensor 6 and a main pipe 7.

Detailed Description

As shown in the attached drawing 1, the utility model discloses in be favorable to the system of rapid judgement thermal power plant high temperature heated surface whether overtemperature is equipped with the work unit 1 that receives the hot surface in a plurality of among the thermal power generation system, specifically be water-cooling wall 11, one-level over heater 12, last level over heater 13, one-level re-heater 14, last level re-heater 15, the female pipe in each work unit 1 exit is last to be connected with sampling pipeline 2 independently, each sampling pipeline 2 extends respectively and passes cooling arrangement 3, install hydrogen concentration detection device 4 (the Orbissphere 510 dissolved hydrogen analyzer of the HACH company of America on each sampling pipeline 2 respectively, its measuring range is 0 ~ 500 mug/L, measurement accuracy is 0.1 mug/L) and is arranged in detecting the hydrogen concentration in the corresponding sampling pipeline 2, each hydrogen concentration detection device 4 respectively system connect in DCS control system 5 (from taking one set of DCS control system 5 and every hydrogen concentration detection device 4 independent system connection's of the same kind of all the way alarm system ),

part of water or steam output from the outlets of the working units 1 passes through a sampling pipeline 2 connected with a main pipe at the outlet of the working unit 1, is cooled by a cooling device 3, then flows through a hydrogen concentration detection device 4 arranged on the sampling pipeline 2,

each working unit 1 is also provided with a conventional heat sensor 6 for detecting the temperature of the heating surface in the working unit 1, and the conventional heat sensor comprises a temperature measuring probe and a display for contacting with the heating surface.

Claims

1. The utility model provides a be favorable to judging fast whether system of thermal power plant high temperature heating surface overtemperature which characterized in that: the system comprises one or more working units (1) with heating surfaces arranged in the thermal power generation system, sampling pipelines (2) are independently connected to a header or a main pipe at the outlet of each working unit (1), each sampling pipeline (2) extends through a cooling device (3) respectively, a hydrogen concentration detection device (4) is mounted on each sampling pipeline (2) and used for detecting the hydrogen concentration in the corresponding sampling pipeline (2), each hydrogen concentration detection device (4) is respectively and systematically connected to a DCS control system (5),

and part of water or steam output from the outlets of the working units (1) passes through the sampling pipeline (2) connected with the header or the main pipe at the outlet of the working unit (1) and is cooled by the cooling equipment (3) and then flows through the hydrogen concentration detection device (4) arranged on the sampling pipeline (2).

2. The system for facilitating a rapid determination of an excess temperature of a high temperature heated surface of a thermal power plant of claim 1, wherein: and each working unit (1) is provided with a conventional thermal sensor (6) for detecting the temperature of a heating surface in the working unit (1).