Real-time monitoring system for carbon dioxide emissions from coal-fired power plants

Abstract

This application relates to carbon emission monitoring technology and discloses a real-time carbon dioxide emission monitoring system for coal-fired power plants, which can accurately, in real-time, and reliably monitor the instantaneous carbon dioxide emission rate of coal-fired power plants. The system includes: an ultrasonic flow meter installed in the flue gas duct for measuring the flue gas flow rate per unit time; a sampling channel connected to the flue gas duct; a sampling pump connected to the sampling channel for drawing flue gas from the sampling channel; a dust removal device, a cooling device, and a carbon dioxide concentration sensor installed in the sampling channel, the sensor being used to detect the carbon dioxide concentration of the flue gas in the sampling channel; and a computing device for multiplying the flue gas flow rate by the carbon dioxide concentration and outputting an electrical signal representing the instantaneous carbon dioxide emission rate.

Description

Technical Field

[0001] This application relates to the field of carbon emission monitoring technology, and in particular to carbon dioxide emission monitoring technology for coal-fired power plants. Background Technology

[0002] This section is intended to provide background or context for understanding the implementation of this application and is for reference only. It should not be construed as an admission by the applicant that this section pertains to prior art that was disclosed before the filing date of this application.

[0003] With increasing global concern about climate change and the gradual implementation of carbon emission control policies, accurate and real-time monitoring of carbon dioxide (CO2) emissions from major stationary emission sources such as coal-fired power plants has become crucial. Carbon dioxide is one of the main greenhouse gases, and effective monitoring of its emissions is fundamental to assessing emission reduction effectiveness, complying with environmental regulations, and participating in carbon trading markets.

[0004] Currently, the common method for determining carbon dioxide emissions from coal-fired power plants is the material balance estimation method. This method estimates carbon dioxide production based on coal consumption, elemental analysis data of coal (especially carbon content), and stoichiometric relationships during combustion. While this method is relatively inexpensive, its accuracy is limited by fluctuations in fuel composition, uncertainties in combustion efficiency, and the precision of coal quantity measurement. Furthermore, it struggles to reflect instantaneous emission fluctuations caused by changes in operating conditions and typically only provides cumulative emission estimates over longer time periods (such as days, months, or years). Summary of the Invention

[0005] The purpose of this application is to provide a real-time monitoring system for carbon dioxide emissions from coal-fired power plants, which can monitor the instantaneous emission rate of carbon dioxide in the flue of coal-fired power plants in real time and accurately.

[0006] This application discloses a real-time monitoring system for carbon dioxide emissions from a coal-fired power plant, comprising:

[0007] An ultrasonic flow meter installed in a flue includes one or more pairs of ultrasonic transceivers installed on the inner wall of the flue. The ultrasonic flow meter is used to measure the flue gas flow rate per unit time in the flue and outputs an electrical signal of the flue gas flow rate.

[0008] A sampling channel connected to the flue;

[0009] A sampling pump connected to the sampling channel is used to extract flue gas from the sampling channel;

[0010] The dust removal device installed in the sampling channel is used to remove dust from the flue gas passing through the sampling channel;

[0011] A cooling device, installed in the sampling channel and located downstream of the dust removal device, is used to cool the flue gas after dust removal.

[0012] A carbon dioxide concentration sensor, installed in the sampling channel and located downstream of the cooling device, is used to detect the carbon dioxide concentration of the flue gas in the sampling channel and output a carbon dioxide concentration electrical signal.

[0013] The computing device has its input terminals electrically connected to the output terminals of the ultrasonic flow meter and the carbon dioxide concentration sensor, respectively. The computing device is used to receive the flue gas flow rate electrical signal and the carbon dioxide concentration electrical signal, multiply the flue gas flow rate by the carbon dioxide concentration, and output an electrical signal representing the instantaneous emission rate of carbon dioxide.

[0014] In the embodiments of this application, a complete system can be constructed by combining an ultrasonic flow meter installed in the flue, a sampling channel connected to the flue and containing dust removal and cooling devices, a carbon dioxide concentration sensor, and a computing device for receiving flow and concentration signals and multiplying them to calculate the instantaneous emission rate. This system enables real-time, online monitoring of the instantaneous carbon dioxide emission rate in the flue of a coal-fired power plant. The system directly measures key parameters (flue gas flow rate and carbon dioxide concentration in the treated sample gas) and calculates them immediately, overcoming the delays and uncertainties of traditional estimation methods or non-real-time measurement methods. It provides emission data with high temporal resolution and accuracy. Simultaneously, flue gas pretreatment (dust removal and cooling) ensures the accuracy of the carbon dioxide sensor measurements and the long-term stable operation of the system.

[0015] Furthermore, by adding a dehumidification device located downstream of the cooling device and upstream of the carbon dioxide concentration sensor, residual moisture in the flue gas sample can be removed more thoroughly, reducing or eliminating the interference of water vapor on the carbon dioxide concentration sensor measurement, thereby improving the accuracy of carbon dioxide concentration measurement, which in turn improves the accuracy of the final calculated instantaneous emission rate, and helps protect the sensor from the influence of moisture.

[0016] Furthermore, by specifically configuring the cooling device as a water-cooled pipe installed in the sampling channel, the readily available cooling water resources in the power plant can be utilized to effectively cool the high-temperature flue gas sample, resulting in a relatively simple structure.

[0017] Furthermore, by specifically configuring the cooling device as a semiconductor cooler, precise, rapid, and controllable adjustment of the sample gas temperature can be achieved, which helps stabilize the sample state to improve the accuracy of subsequent measurements. It is also typically compact in structure, easy to integrate, and can be automated.

[0018] Furthermore, by setting the connection point between the sampling channel and the flue upstream of the location of one or more pairs of ultrasonic transceivers along the flue gas flow direction, the travel time of the flue gas from the connection point of the sampling channel to the ultrasonic transceiver in the flue gas can be used to compensate for the delay time of the flue gas in the sampling channel from the sampling channel opening to the carbon dioxide concentration sensor, making the signals output by the ultrasonic flow meter and the carbon dioxide concentration sensor more matched in time.

[0019] Furthermore, by setting a buffer between the ultrasonic flow meter and the computing device to buffer and delay the transmission of the flue gas flow electrical signal, and setting a delay time to compensate for the time it takes for the flue gas to travel from the connection point between the sampling channel and the flue to the carbon dioxide concentration sensor, it can be ensured that the flow signal and concentration signal used by the computing device for multiplication correspond to the same flue gas in time, eliminating the time mismatch caused by sample transmission lag, thereby improving the accuracy of the calculated instantaneous carbon dioxide emission rate. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure of a real-time monitoring system for carbon dioxide emissions from a coal-fired power plant according to an embodiment of this application. Detailed Implementation

[0021] In the following description, many technical details are presented to help the reader better understand this application. However, those skilled in the art will understand that the technical solutions claimed in this application can be implemented even without these technical details and various variations and modifications based on the following embodiments.

[0022] To make the objectives, technical solutions, and advantages of this application clearer, the embodiments of this application will be described in further detail below with reference to the accompanying drawings.

[0023] The embodiments of this application relate to a real-time monitoring system for carbon dioxide emissions from a coal-fired power plant, such as... Figure 1 As shown, the real-time carbon dioxide emission monitoring system of this coal-fired power plant includes:

[0024] An ultrasonic flow meter, installed inside a flue, comprises one or more pairs of ultrasonic transceivers mounted on the inner wall of the flue. The ultrasonic flow meter measures the flow rate of flue gas per unit time within the flue and outputs an electrical signal indicating the flow rate. Its principle is based on calculating the time difference between the forward and reverse propagation of ultrasonic waves. This electrical signal can be a digital signal. Ultrasonic flow meters are existing technology and will not be described in detail here.

[0025] A sampling channel connected to the flue at one end. This sampling channel contains, in sequence, a dust removal device, a cooling device, a dehumidification device, a carbon dioxide concentration sensor, and a sampling pump.

[0026] A dust removal device is used to remove dust from the flue gas passing through the sampling channel. The dust removal device can be an air filter.

[0027] A cooling device, located downstream of the dust removal device, is used to cool the flue gas after dust removal. Optionally, in one embodiment, the cooling device is a water-cooling system with water-cooled pipes installed in the sampling channel to achieve heat exchange.

[0028] A dehumidification device, located downstream of the cooling device, is used to dehumidify the cooled flue gas. This dehumidification device is optional. For example, when a powerful cooling device is used, water vapor in the flue gas can be condensed, achieving dehumidification while cooling, thus eliminating the need for a separate dehumidification device.

[0029] A carbon dioxide concentration sensor, positioned in or downstream of a cooling device, detects the carbon dioxide concentration in the flue gas within the sampling channel and outputs an electrical signal indicating the carbon dioxide concentration. This electrical signal can be digital. Preferably, the carbon dioxide concentration sensor can be a non-dispersive infrared carbon dioxide sensor. This non-dispersive infrared carbon dioxide sensor emits infrared light of a specific wavelength, which passes through the flue gas sample to be tested, and then measures how much infrared light is absorbed by carbon dioxide molecules. The degree of absorption is proportional to the carbon dioxide concentration.

[0030] A sampling pump, used to extract flue gas from a sampling channel, can be installed at one end of the sampling channel.

[0031] The real-time monitoring system for carbon dioxide emissions from coal-fired power plants also includes a computing device, whose input terminals are electrically connected to the output terminals of the ultrasonic flow meter and the carbon dioxide concentration sensor, respectively. The computing device is used to receive the flue gas flow rate electrical signal and the carbon dioxide concentration electrical signal, and multiply the flue gas flow rate by the carbon dioxide concentration to output an electrical signal representing the instantaneous emission rate of carbon dioxide.

[0032] There are several ways to implement a computing device. One method is to simply use a multiplier circuit, which multiplies the two input signals and outputs the result. Multiplier circuits are existing technology and will not be discussed in detail here. Another method is to use a processor to perform the multiplication operation; processors typically have multiplication functionality. Both multipliers and processors are mature existing technologies and will not be discussed in detail here.

[0033] If the carbon dioxide concentration sensor is placed directly in the flue, the requirements for its high temperature resistance, corrosion resistance, and dust pollution resistance would be very high. Therefore, this application places the carbon dioxide concentration sensor in the sampling channel. However, there is a certain distance between the sampling channel inlet and the carbon dioxide concentration sensor, and the carbon dioxide concentration measured by the sensor is not real-time data at the interface between the flue and the sampling channel, but rather has a slight delay. The ultrasonic flow meter measures the real-time flue gas flow rate in the flue; therefore, the output data of the carbon dioxide concentration sensor may have some delay relative to the output data of the ultrasonic flow meter. The following describes two methods to mitigate or correct this delay.

[0034] Optionally, in one embodiment, the connection point between the sampling channel and the flue is located upstream of one or more pairs of ultrasonic transceivers along the flue gas flow direction. In this way, the flue gas flow rate measured by the ultrasonic flow meter is delayed relative to the connection point between the sampling channel and the flue, allowing the output data of the carbon dioxide concentration sensor to be more time-matched with the output data of the ultrasonic flow meter.

[0035] Optionally, in another embodiment, a buffer can be provided between the ultrasonic flow meter and the computing device. The buffer buffer is used to buffer the flue gas flow electrical signal and send it to the computing device after a preset delay time. The preset delay time is used to compensate for the transmission time of the flue gas from the ultrasonic flow meter measurement position in the flue to the carbon dioxide concentration sensor, or to compensate for the time difference between the flue gas flow electrical signal and the carbon dioxide concentration electrical signal. The buffer can be implemented using N (N is a positive integer) cascaded flip-flops. In each clock cycle, each flip-flop passes the data it originally stored to the next flip-flop, so that the buffer can transmit the received data after N clock cycles.

[0036] Optionally, in one embodiment, the cooling device includes a semiconductor cooler. In this real-time monitoring system for instantaneous carbon dioxide emissions from a coal-fired power plant, the semiconductor cooler is primarily used for cooling and dehumidifying flue gas samples. The semiconductor cooler has a semiconductor cooling chip. When direct current passes through the cooling chip, one side absorbs heat and becomes cold (cold end), while the other side releases heat and becomes hot (hot end). The semiconductor cooler also includes a heat exchanger (typically made of a thermally conductive metal, such as aluminum alloy or stainless steel, with internal gas channels), with the cold end of the cooling chip tightly attached to this heat exchanger. The still relatively hot flue gas sample containing moisture from the dust removal device flows through the internal channels of this heat exchanger. As the flue gas flows through the forcibly cooled heat exchanger channels, its temperature drops rapidly. When the temperature drops below the dew point temperature of the water vapor in the flue gas, the water vapor condenses into liquid water droplets on the inner wall of the channels. The hot end of the cooling chip needs to dissipate heat effectively to maintain the low temperature of the cold end. Typically, heat sinks are installed at the hot end, and a fan is often used for forced air cooling to dissipate heat into the surrounding environment. Downstream of the heat exchanger, before the gas enters the carbon dioxide sensor, there is a gas-liquid separator or condensate collection and discharge device to collect the condensed liquid water and discharge it from the system manually, automatically (such as by a peristaltic pump at regular intervals), or by gravity, to prevent the liquid water from entering subsequent sensors.

[0037] Semiconductor coolers precisely regulate the temperature of the cold junction by controlling the supply current or voltage. They are typically used in conjunction with temperature sensors and controllers (such as PID controllers) to precisely control the outlet gas temperature of the heat exchanger at a low, stable value (e.g., around the dew point +4°C). This ensures that the flue gas is adequately cooled and most water vapor is effectively removed, while preventing water from freezing and clogging the pipes. Semiconductor coolers cool high-temperature flue gas to a temperature range suitable for sensor operation, removing water vapor, which can interfere with or absorb measurements from carbon dioxide sensors (especially non-dispersive infrared (NDIR) sensors), leading to reading deviations. Simultaneously, a stable sample temperature also contributes to improved measurement stability. Semiconductor coolers also prevent condensation from accumulating inside pipes or sensors, causing corrosion, blockage, or damage.

[0038] It should be noted that, in this application, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one" does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0039] This specification includes combinations of various embodiments described herein. Individual references to embodiments (e.g., “one embodiment”, “some embodiments”, or “preferred embodiments”) do not necessarily refer to the same embodiment; however, these embodiments are not mutually exclusive unless indicated to be mutually exclusive or are readily apparent to those skilled in the art.

[0040] Furthermore, it should be understood that after reading the contents of this application, those skilled in the art can make various alterations or modifications to this application, and these equivalent forms also fall within the scope of protection claimed in this application.

Claims

1. A real-time monitoring system for carbon dioxide emissions from a coal-fired power plant, characterized by, include: An ultrasonic flow meter installed in a flue includes one or more pairs of ultrasonic transceivers installed on the inner wall of the flue. The ultrasonic flow meter is used to measure the flue gas flow rate per unit time in the flue and outputs an electrical signal of the flue gas flow rate. A sampling channel connected to the flue; A sampling pump connected to the sampling channel is used to extract flue gas from the sampling channel; The dust removal device installed in the sampling channel is used to remove dust from the flue gas passing through the sampling channel; A cooling device, installed in the sampling channel and located downstream of the dust removal device, is used to cool the flue gas after dust removal. A carbon dioxide concentration sensor, installed in the sampling channel and located downstream of the cooling device, is used to detect the carbon dioxide concentration of the flue gas in the sampling channel and output a carbon dioxide concentration electrical signal. The computing device has its input terminals electrically connected to the output terminals of the ultrasonic flow meter and the carbon dioxide concentration sensor, respectively. The computing device is used to receive the flue gas flow rate electrical signal and the carbon dioxide concentration electrical signal, multiply the flue gas flow rate by the carbon dioxide concentration, and output an electrical signal representing the instantaneous emission rate of carbon dioxide.

2. The real-time monitoring system for carbon dioxide emission of coal-fired power plants according to claim 1, characterized in that, It also includes a dehumidification device, which is located in the sampling channel and downstream of the cooling device and upstream of the carbon dioxide concentration sensor, for dehumidifying the cooled flue gas.

3. The real-time monitoring system for carbon dioxide emission of coal-fired power plants of claim 1, wherein, The cooling device includes a water-cooled pipe installed in the sampling channel.

4. The real-time monitoring system for carbon dioxide emission of coal-fired power plants of claim 1, wherein, The cooling device includes a semiconductor cooler.

5. The real-time monitoring system for carbon dioxide emission from coal-fired power plants of claim 1, wherein, The carbon dioxide concentration sensor is a non-dispersive infrared carbon dioxide sensor.

6. The real-time monitoring system of carbon dioxide emission of coal-fired power plant of claim 1, wherein, The dust removal device includes a filter.

7. The real-time monitoring system of carbon dioxide emission of coal-fired power plant of claim 1, wherein, The computing device includes a multiplier.

8. The real-time monitoring system for carbon dioxide emissions from coal-fired power plants according to any of claims 1 to 7, characterized in that, The sampling channel is positioned upstream of the location of the one or more pairs of ultrasonic transceivers along the flue gas flow direction.

9. The real-time monitoring system for carbon dioxide emissions from coal-fired power plants according to any of claims 1 to 7, characterized in that, It also includes a buffer disposed between the ultrasonic flow meter and the computing device. The buffer is used to buffer the flue gas flow electrical signal and send it to the computing device after a preset delay time. The preset delay time is used to compensate for the transmission time of the flue gas from the ultrasonic flow meter measurement position in the flue to the carbon dioxide concentration sensor.

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