A method and system for measuring net flue gas flow

Abstract

The present invention discloses a method and system for measuring the net flue gas flow rate, which can release a tracer in the flue between the original flue gas CEMS sampling point and the inlet of the desulfurization equipment, obtain the tracer concentration after passing through the desulfurization equipment through the clean flue gas CEMS probe, and combine the tracer method to accurately obtain the net flue gas flow rate. In addition, by selecting CO gas that does not participate in the chemical reaction of the desulfurization equipment as a tracer, good mixing of the tracer and the flue gas can be guaranteed. Secondly, the tracer can be diffused in the flue by rotating blades to further improve the mixing effect.

Description

Technical Field

[0001] The present invention relates to the technical field of flue gas treatment, and in particular to a method and system for measuring net flue gas flow. Background Art

[0002] At present, the velocity-area method is commonly used to measure static flue gas flow in thermal power plants. The velocity-area method is divided into point measurement, line measurement and surface measurement. This measurement method has high requirements on the straight pipe sections before and after the measuring point, generally at least four in front and two in the back. However, most thermal power plants currently do not meet this condition, resulting in large deviations in the measurement of net flue gas flow in thermal power plants. Moreover, with the increasing requirements for the accuracy of flue gas pollutant emissions and carbon dioxide emissions, the existing CEMS flow measurement method can no longer meet the requirements.

[0003] Therefore, how to improve the measurement accuracy of net flue gas flow rate is a technical problem that technical personnel in this field urgently need to solve. Summary of the invention

[0004] The purpose of the present invention is to provide a method and system for measuring net flue gas flow, which can effectively solve the problem of large deviation in net flue gas flow measurement.

[0005] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0006] A method for measuring net flue gas flow rate comprises the following steps:

[0007] Release the tracer in the flue between the original flue gas CEMS sampling point and the desulfurization equipment inlet;

[0008] Obtaining the tracer concentration after passing through the desulfurization equipment;

[0009] According to the tracer concentration, the net flue gas flow is obtained.

[0010] Preferably, the raw flue gas measurement parameters obtained at the raw flue gas CEMS sampling point include: raw flue gas temperature t1; raw flue gas moisture content X 1sw ; Original flue gas static pressure p1; Original flue gas CO concentration C 1CO ;Oxygen content of original flue gas

[0011] Before obtaining the net flue gas flow, the following parameters are also obtained:

[0012] Environmental parameters: atmospheric pressure B a ;

[0013] Clean flue gas measurement parameters: clean flue gas temperature t2; clean flue gas moisture content X 2sw ; Net flue gas static pressure p2; Net flue gas CO concentration C 2CO ; Net flue gas oxygen content

[0014] Tracer parameters: Tracer flow rate Q sz ; Tracer concentration C CO ;

[0015] Dilution factor: Dilution factor of water evaporation in wet desulfurization Dilution coefficient of air leakage in pipeline and desulfurization device

[0016]

[0017]

[0018] The net flue gas flow rate Q before water and air dilution is calculated by the following formula:

[0019]

[0020] The wet clean flue gas flow rate Q2 without considering the temperature and pressure changes is calculated by the following formula:

[0021]

[0022] Wet clean flue gas flow Q under actual working conditions 2s , calculated by the following formula:

[0023]

[0024] Clean flue gas flow rate Q under standard conditions 2sn , calculated by the following formula:

[0025]

[0026] Preferably, the tracer concentration after passing through the desulfurization equipment is obtained by a clean flue gas CEMS probe.

[0027] Preferably, the tracer released in the flue is CO gas.

[0028] Preferably, the tracer released into the flue is diffused by rotating blades.

[0029] A clean flue gas flow measurement system comprises a tracer release device arranged at the flue between the original flue gas CEMS probe and the desulfurization equipment inlet, a clean flue gas CEMS probe is arranged at the flue behind the desulfurization equipment outlet, and the clean flue gas CEMS probe is used to detect the tracer concentration.

[0030] Preferably, the tracer release device comprises a tracer gas cylinder, a tracer release probe, and a rotating blade. The tracer gas cylinder is used to deliver the tracer to the tracer release probe. The rotating blade is arranged at the outlet of the tracer release probe, and the rotating blade is driven by the airflow in the flue.

[0031] Preferably, the rotating blades are provided with air holes.

[0032] Preferably, it also includes a flow detection device for detecting the tracer released from the tracer gas cylinder.

[0033] Preferably, it also includes a regulating valve for controlling the release amount of the tracer.

[0034] Compared with the prior art, the above technical solution has the following advantages:

[0035] The net flue gas flow measurement method and system provided by the present invention can release a tracer in the flue between the original flue gas CEMS sampling point and the inlet of the desulfurization equipment, obtain the tracer concentration after passing through the desulfurization equipment through the clean flue gas CEMS probe, and combine the tracer method to accurately obtain the net flue gas flow. In addition, by selecting CO gas that does not participate in the chemical reaction of the desulfurization equipment as a tracer, good mixing of the tracer and the flue gas can be guaranteed. Secondly, the tracer can be diffused in the flue by rotating blades to further improve the mixing effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0037] Figure 1 A schematic diagram of a net flue gas flow measurement system provided by a specific embodiment of the present invention;

[0038] Figure 2 This is a front view of the rotating blade.

[0039] 1 is the flue, 2 is the desulfurization equipment, 3 is the original flue gas CEMS probe, 4 is the clean flue gas CEMS probe, 5 is the tracer release probe, 6 is the rotating blade, 7 is the air hole, 8 is the flow detection device, and 9 is the tracer gas cylinder. DETAILED DESCRIPTION

[0040] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and understandable, the specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0041] In the following description, specific details are set forth to facilitate a full understanding of the present invention. However, the present invention can be implemented in a variety of other ways than those described herein, and those skilled in the art can make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0042] A specific embodiment of the present invention provides a method for measuring net flue gas flow, which is preferably applied to thermal power plants, and specifically measures the real-time flow of net flue gas by a tracer method, wherein the measurement method comprises the following steps:

[0043] Step 1: Release the tracer in the flue between the original flue gas CEMS sampling point and the desulfurization equipment inlet. In order to ensure that the tracer does not participate in the chemical reaction of the desulfurization equipment and has good mixing with the flue gas, the tracer is preferably CO gas.

[0044] Step 2: Obtain the tracer concentration after passing through the desulfurization equipment. Specifically, the tracer concentration after passing through the desulfurization equipment is obtained through the clean flue gas CEMS probe. That is, the tracer CO concentration monitoring method is consistent with the gaseous pollution monitoring method. The original flue gas CEMS probe and the clean flue gas CEMS probe are not changed, thereby saving construction and modification costs.

[0045] Step 3: Obtain the net flue gas flow rate according to the tracer concentration. The tracer measurement method can refer to the existing technology and will not be described here. The existing CEMS measurement method is modified by the tracer measurement principle to improve the measurement accuracy of the net flue gas flow rate and reduce the measurement cost.

[0046] When facing the complex flue environment of a thermal power plant, the specific measurement method is as follows:

[0047] The original flue gas measurement parameters obtained at the original flue gas CEMS sampling point include: original flue gas temperature t1 (℃); original flue gas moisture content X 1sw (%); original flue gas static pressure p1(p a ); original flue gas CO concentration C 1CO (ppm); original flue gas oxygen content

[0048] Before calculating the net flue gas flow, the following parameters need to be obtained:

[0049] Environmental parameters: atmospheric pressure Ba (p a );

[0050] Clean flue gas measurement parameters: clean flue gas temperature t2 (℃); clean flue gas moisture content X 2Bw (%); Net flue gas static pressure p2(p a ); Net flue gas CO concentration C 2CO (ppm); net flue gas oxygen content

[0051] Tracer parameters: Tracer flow rate Q ss ; Tracer concentration C CO (ppm);

[0052] Net flue gas flow rate: Flue gas flow rate Q (m 3 / h); without considering the change of temperature and pressure, the wet flue gas flow rate Q2 (m 3 / h); wet flue gas flow rate Q under actual working conditions 2s (m 3 / h); dry flue gas flow rate Q under standard conditions 2sn (m 3 / h);

[0053] Dilution factor (the ratio of volume after dilution to volume before dilution): Dilution factor of water evaporation in wet desulfurization Dilution coefficient of air leakage in pipeline and desulfurization device

[0054]

[0055]

[0056] The net flue gas flow rate Q before water and air dilution is calculated by the following formula:

[0057]

[0058] The wet clean flue gas flow rate Q2 without considering the temperature and pressure changes is calculated by the following formula:

[0059]

[0060] Wet clean flue gas flow Q under actual working conditions 2s , calculated by the following formula:

[0061]

[0062] Clean flue gas flow rate Q under standard conditions 2m , calculated by the following formula:

[0063]

[0064] Through the above measurement method, the problems of air leakage and water evaporation in wet flue gas desulfurization equipment are fully considered, so the measurement accuracy of net flue gas flow can be further improved.

[0065] The embodiment of the present invention also provides a net flue gas flow measurement system, which is preferably applicable to thermal power plants, please refer to Figure 1 and Figure 2The measurement system includes a tracer release device arranged at the flue 1 between the original flue gas CEMS probe 3 and the inlet of the desulfurization equipment 2. The desulfurization process is generally a wet process, a dry process and a semi-dry process, that is, the measurement system is applicable to the above desulfurization process, especially to the wet desulfurization process of thermal power plants. A clean flue gas CEMS probe 4 is provided at the flue 1 behind the outlet of the desulfurization equipment 2, wherein the tracer concentration can be detected by the clean flue gas CEMS probe 4. The purpose of obtaining the tracer concentration is to calculate the net flue gas flow rate by the tracer method, and the tracer method can effectively improve the accuracy of the net flue gas flow rate measurement. During specific operation, the tracer releasing device can release the tracer in the flue 1. To ensure that the tracer does not participate in the chemical reaction of the desulfurization equipment 2 and has good miscibility with the flue gas, the tracer is preferably CO gas, wherein the tracer CO concentration monitoring module is respectively installed in the original flue gas and clean flue gas gaseous pollutant concentration analysis cabinets. To ensure better compatibility, the tracer CO concentration monitoring method is consistent with the gaseous pollution monitoring method, and the original flue gas CEMS probe 3 and the clean flue gas CEMS probe 4 are not modified to save construction and modification costs.

[0066] Specifically, the tracer release device includes a tracer gas cylinder 9, a tracer release probe 5, and a rotating blade 6. The tracer release probe 5 is located in the flue 1, and the rotating blade 6 is arranged at the outlet of the tracer release probe 5. During specific operation, the tracer gas cylinder 9 transports the tracer to the tracer release probe 5. The airflow direction is as follows: Figure 1 As shown by the arrow in , when the flue gas flows through the rotating blades 6, the airflow can drive the rotating blades 6 to rotate to ensure that the tracer gas and the flue gas are fully mixed and uniform, wherein the rotating blades 6 are driven to rotate by the airflow, which can save power devices.

[0067] Among them, the rotating blades 6 are provided with air holes 7, and the specific number of the rotating blades 6 can be determined according to actual conditions, wherein four pieces are preferably provided, and each rotating blade 6 is provided with an air hole 7, and the air hole 7 is connected with the outlet of the tracer release probe 5 to ensure that the tracer is dispersed and released in the flue 1, so that the tracer and the flue gas are fully mixed.

[0068] Furthermore, it also includes a flow detection device 8 for detecting the tracer released by the tracer gas cylinder 9. The tracer volume in the tracer gas cylinder 9 can be known through the flow detection device 8, so as to replenish the tracer. In addition, it also includes a regulating valve for controlling the release amount of the tracer, and the smooth flow of the tracer can be ensured by adjusting the valve.

[0069] It should be noted that, in this article, terms such as "comprises", "includes" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of more restrictions, an element defined by the sentence "comprises a ..." does not exclude the existence of other identical elements in the process, method, article or device including the element.

[0070] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for measuring net flue gas flow, characterized in that: include: Release the tracer in the flue between the original flue gas CEMS sampling point and the desulfurization equipment inlet, and diffuse the tracer released in the flue through the rotating blades; Obtaining the tracer concentration after passing through the desulfurization equipment; According to the tracer concentration, obtaining a net flue gas flow rate; The raw flue gas measurement parameters obtained at the raw flue gas CEMS sampling point include: raw flue gas temperature ; Moisture content of original flue gas ; Original flue gas static pressure ; Original flue gas concentration ;Oxygen content of original flue gas ; Before obtaining the net flue gas flow, the following parameters are also obtained: Environmental parameters: atmospheric pressure ; Net flue gas measurement parameters: Net flue gas temperature ; Net flue gas moisture content ; Net flue gas static pressure ; Clean flue gas concentration ; Net flue gas oxygen content ; Tracer parameters: Tracer flow rate ; Tracer concentration ; Dilution factor: Dilution factor of water evaporation in wet desulfurization ; Dilution coefficient of air leakage in pipelines and desulfurization equipment ; ； ； Net flue gas flow before moisture and air dilution , calculated by the following formula: ； Wet clean flue gas flow without considering temperature and pressure changes , calculated by the following formula: ； Wet clean flue gas flow rate under actual working conditions , calculated by the following formula: ； Clean flue gas flow rate under standard conditions , calculated by the following formula: 。 2. The method for measuring the net flue gas flow rate according to claim 1, characterized in that: The tracer concentration after passing through the desulfurization equipment is obtained through the clean flue gas CEMS probe.

3. The net flue gas flow measurement method according to claim 2, characterized in that: The tracer released in the flue is CO gas.

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