Patent Application
20250164108
This application is based upon and claims priority to Chinese Patent Application 202311537796.X, filed on Nov. 17, 2023, the entire contents thereof are incorporated herein by reference.
This disclosure belongs to the field of burners and relates to a novel and unique premixed combustion device designed to meet various demands with a wide adjustment ratio, high efficiency, energy saving and safety. This disclosure also relates to an adjusting device for a gas burner.
Gas burners comprise cast aluminum condensing gas burner, gas boiled water burner, gas hot water burner, gas steam burner and the like, wherein the cast aluminum condensing hot water burner is also known as gas heating burner and gas bathing burner. As the name implies, gas burner uses gas as fuel, which can be natural gas, LNG, CNG, coal gas, etc. After several years of practical data collection and comparison in winter heating, it has been found that cast aluminum condensing gas burner is more energy-efficient than ordinary gas burner, oil burner, and electric boiler in heating and bathing applications.
The combustion regulation ratio, also called the modulation ratio, is the ratio of the maximum to the minimum combustion capacity allowed under stable combustion conditions. The modulation ratio is a characteristic index for evaluating combustion stability. Combustion stability comprises two concepts: one is the stability of the heat balance state in the combustion chamber, meaning the heat released in the combustion chamber per unit time should balance with the heat dissipated from the combustion system per unit time, otherwise, combustion may be interrupted; the other is the stability of the flame position, ensuring no backfire or flameout, forming a stable temperature field. The load of a burner's combustion device must be adjusted according to the thermal requirements of the burner, but during the adjustment process, combustion stability must be maintained. The larger the modulation ratio, the better the combustion stability of the device and process, meaning it allows load adjustment within a larger range while maintaining stable combustion.
Fully premixed combustion refers to a method in which air and gas are pre-mixed in a mixing device in a specific ratio, and the mixed premixed gas is then sent to the combustion device for combustion. Water-cooled premixed combustion is a type of fully premixed combustion where the flame is cooled with water. Each fully premixed burner includes a combustion fan, a gas valve, a mixer, and a combustion device. The larger the volume of the mixing device, the harder it is to achieve uniform mixing. Similarly, the larger the volume of a single combustion device, the more difficult it is to achieve uniform combustion, and once problems occur, the risk of flashback and explosion increases. The above two reasons limit the power of a single fully premixed burner. According to data, the maximum power of a fully premixed burner to date does not exceed 7 MW.
Some embodiments of present disclosure aims at reduce combustion temperature to achieve low NOX emissions, increase the combustion area to significantly enhance the power of a single burner (a single premixed burner power of more than 50 MW can be achieved), and to realize a higher combustion adjustment ratio (a single premixed burner adjustment ratio of more than 1:20 can be achieved) while meeting different steam demands from customer and maintaining high combustion efficiency. Some embodiment aims to overcome the defects of the prior art and provides an adjusting device for gas burner that can achieve large-ratio modulation of the combustion modulation ratio.
To achieve the above objective, some embodiment adopts the following technical solution: An adjusting device for gas burner comprises a distribution chamber with a static pressure chamber formed inside. The distribution chamber is provided with a main vent and several secondary vents connected to the static pressure chamber. The distribution chamber is provided with a sealing mechanism for blocking the secondary vents, including a cylinder and a seal driven by the cylinder, controlling the switch of the secondary vents. The sealing mechanism has an air release vent for discharging excess air volume. The distribution chamber is also provided with an air inlet connected to the static pressure chamber, and the main vent is always in connection with the static pressure chamber.
Both the main and secondary vents are connected to corresponding combustion zones. The seal in the sealing mechanism, driven by the cylinder, seals the secondary vents, blocking the air intake for the corresponding combustion zones, effectively shutting off the combustion in the secondary vent areas. Excess air volume is discharged into the atmosphere through the air release vent, allowing the burner to achieve ultra-low load combustion under normal flue gas emission conditions, thereby achieving large-ratio modulation and ensuring burner combustion efficiency.
According to some embodiments, the sealing mechanism comprises a flange plate set on the distribution chamber, with the cylinder fixedly set on the flange plate.
According to some embodiments, the flange plate has a guide rail for guiding the seal. The guide rail is set in the static pressure chamber, extending to the secondary vent.
Each sealing mechanism is provided with a single guide rail to ensure the precision of the seal's forward and backward movement, minimizing constraints on the seal, preventing jamming during movement, and ensuring the normal operation of the sealing mechanism.
According to some embodiments, the flange plate has a fixing element for fixing the guide rail, with the guide rail passing through the fixing element.
According to some embodiments, the seal is sleeved with a slider, which is slidably connected to the guide rail and moves synchronously with the seal.
The slider slides on the guide rail, driving the seal to move smoothly on the guide rail, ensuring the seal from jamming, thereby ensuring the normal operation of the sealing mechanism.
According to some embodiments, the cylinder's output end has a floating joint for controlling the movement of the seal.
According to some embodiments, the seal has a connector connected to the floating joint.
The floating joint is connected to the connector on the seal, ensuring accurate connection between the cylinder's output end and the seal, reducing manufacturing and assembly errors, and improving the connection accuracy between the floating joint and the connector.
According to some embodiments, the air release vent comprises a first vent and a second vent formed on the flange plate, set on opposite sides of the cylinder.
According to some embodiments, the first vent has an adjustment plate for adjusting the size of the first vent.
The adjustment plate adjusts the opening size of the first vent, regulating the amount of air discharged from the static pressure chamber, ensuring the modulation ratio of the gas burner meets usage requirements, and improving combustion efficiency.
According to some embodiments, the second vent is provided with a limit switch for transmitting the signal that the seal has sealed the air release vent.
The embodiments of this disclosure are described in detail below with reference to the drawings.
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Additionally, the distribution chamber 2 is welded from multiple plates with a bottom cover. The main vent 103 and secondary vents 104 are on the rear side of the distribution chamber 2, with secondary vents 104 on both sides of the main vent 103, all connected to the combustion zone of the gas burner. The air inlet 102 is at the center of the bottom of the distribution chamber 2, allowing air to enter the static pressure chamber 101 and then pass through the main vent 103 and secondary vents 104 into the combustion zone. Under the action of the sealing mechanism 2, the secondary vents 104 can be opened and closed to adjust the air volume entering the combustion zone, enabling the burner to achieve ultra-low load combustion under normal flue gas emissions, thus achieving a large adjustment ratio and ensuring burner combustion efficiency.
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Using a cylinder 202 as the driving mechanism avoids the high precision requirements of limit control with servo motors or electric push rods. The seal 204 is provided with a sealing ring to ensure no air leakage when sealing the secondary vents 104, thus ensuring effective sealing.
The flange plate 201 has a guide rail 203 for guiding the seal 204. The guide rail 203 is positioned within the static pressure chamber 101 and extends to the secondary vent 104. There is one guide rail 203, vertically positioned on the flange plate 201, designed as a cylindrical rod. This single cylindrical guide rail 203 ensures the precision of the seal 204's forward and backward movement while minimizing constraints, preventing jamming during the movement of the sealing mechanism 2 and ensuring its normal operation. Additionally, positioning the guide rail 203 at the secondary vents 104 ensures that the seal 204 does not detach from the guide rail 203 during sealing.
The flange plate 201 has a fixing element 2031 for securing the guide rail 203. The guide rail 203 passes through the fixing element 2031, which is positioned on the same side as the cylinder 202. The guide rail 203 is fixedly connected to the fixing element 2031, securing the guide rail 203. The seal 204 has a slider 2041 mounted on it, which is slidingly connected to the guide rail 203.
The seal 204 is fitted with a slider 2041, which is slidably connected to the guide rail 203. The slider 2041 and the seal 204 moves synchronously. Furthermore, the slider 2041 and the seal 204 are fixedly connected by bolts. The slider 2041 is fitted on the guide rail 203, and it drives the movement of the seal 204. This ensures that the seal 204 does not jam during movement and ensure low constraint on the seal 204 during the movement.
The output end of the cylinder 202 is provided with a floating joint 2021 to control the movement of the seal 204. The seal 204 has a connector 2043 connected to the floating joint 2021. The floating joint 2021 is threaded onto the cylinder 202's output end and is a standard part compatible with the cylinder 202. The connection between the floating joint 2021 and the connector 2043 achieves initial positioning of the floating joint 2021 and ensures accuracy of their connection. When the floating joint 2021 is connected to the connector 2043, the cylinder 202 pushes the floating joint 2021 to move, thereby moving the connector 2043.
The vent 206 comprises a first vent 2061 and a second vent 2062 on the flange plate 201, positioned on opposite sides of the cylinder 202. When the seal 204 seals the secondary vents 104, air entering the static pressure chamber 101 from the air inlet 102 is discharged through the first vent 2061 and second vent 2062, preventing excessive pressure buildup in the static pressure chamber 101.
The first vent 2061 has an adjustment plate 2011 for size adjustment, fixed on the flange plate 201 with several bolt holes on the edge and corresponding holes are also set around the first vent 2061. By adjusting the fixed position of the adjustment plate 2011 according to the pressure in the static pressure chamber 101, the size of the first vent 2061 can be regulated. This, in turn, allows for the adjustment of the amount of air discharged from the static pressure chamber 101, ensuring that the regulation ratio of the gas burner meets operational requirements and thereby improving the combustion efficiency of the gas burner.
A limit switch 205 is installed at the second vent 2062 to transmit the signal that the seal 204 has sealed the vent 206. Furthermore, the limit switch 205 is fixedly installed on the flange plate 201, and the limit switch 205 is located directly above the second vent 2062. A limit element 2042 is vertically installed on the seal 204 and corresponds to the limit switch 205. When the seal 204 moves towards the flange plate 201 and the limit element 2042 moves into the second vent 2062, the limit element 2042 contacts the limit switch 205. The limit switch 205 then transmits the signal that the seal 204 has sealed the vent 206 to the controller, informing the system that the vent 206 is sealed, allowing the process to proceed to the next step.
In practical application, the adjusting device features one main vent 103 and two secondary vents 104, corresponding to three combustion zones in the burner. Normal combustion is achieved when all three zones are ignited, allowing load adjustment. When steam pressure is low, the load increases; as pressure nears or exceeds the target, the load decreases; and if pressure exceeds the safety limit, the burner shuts down. The target and safety pressures have a narrow range in between. With this device, four additional pressure values are set: multi-zone closing values A and B, and multi-zone opening values A and B. Multi-zone closing values A and B control the shutdown of the left and right combustion zones of the burner, multi-zone opening values A and B control the ignition of the left and right combustion zones of the burner.
Take the following data as an example: assuming the target pressure is 1.0 MPA, safety pressure is 1.1 MPA, multi-zone closing values A is 0.02 and B is 0.04, and multi-zone opening values A is −0.02 and B is −0.04.
The above descriptions of the disclosed embodiments allow those skilled in the art to realize or use some embodiment. Various modifications will be apparent to those skilled in the art, and the general principles defined here can be applied in other embodiments without departing from the spirit or scope of some embodiment. Therefore, some embodiment will not be limited to the disclosed embodiments but will align with the broadest scope consistent with the principles and novel features disclosed herein.
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The cooling tube array, flame stabilizing tube array, water distribution chamber, and water collection chamber are interconnected, with water as the internal medium. The shapes of the tubes forming the cooling and flame stabilizing tube arrays are varied, including but not limited to cylindrical, rectangular, and finned tubes.
Each component of the burner is interconnected to form a closed passage. First, air is sent into the burner by the fan, and the distribution chamber distributes the air to different combustion channels. The gas is distributed to each gas valve subassembly through the gas main pipe. Air and gas are mixed in the mixer to form a premixed gas, which undergoes further mixing in the premixing device. The premixed gas then enters the tail outlet of the burner to form combustion surface. Multiple combustion channels form multiple combustion surfaces.
The distribution chamber has multiple air outlets, allowing the air to be evenly distributed to different combustion channels. It is provided with a sealing mechanism that can independently control the switch and air discharge of each combustion channel, thereby achieving a super-large combustion adjustment ratio.
The arrangement of each surface of the multi-surface burner can be adjusted according to the design of the boiler body, and the number of combustion surfaces can be increased or decreased according to different power requirements.
A gas valve assembly, a premixing device, and a water-cooled flame stabilizing tube array (all with variable shapes and structures) form a single combustion channel. A multi-combustion surfaces water-cooled premixed burner with a high adjustment ratio features multiple combustion channels, achieving high-power output for a single burner without increasing the number of devices or fans. This allows for fully premixed combustion of up to 50 MW with a simple structure, small size, and low cost, which overcomes the issue of individual burners not achieving high-power output in prior art. Multiple combustion channels are interconnected by distribution chamber, water distribution chamber and water collection chamber to form an integrated system. To facilitate the circulation of cooling medium, water distribution chamber is provided at the top of each water-cooled flame-stabilizing tube array and water collection chamber is provided at the bottom. The number of combustion channels can be flexibly adjusted.
At the burner head, there is an air supply device. During operation, the required heat amount controls the fan frequency and the air damper opening to adjust the air volume and pressure. The gas valve assembly then automatically adjusts the gas volume based on the changes in air pressure. When the required heat increases, the fan frequency rises, and the air damper opens wider, increasing air volume and pressure, and consequently, the gas valve assembly also opens wider. Conversely, when the required heat decreases, the fan frequency drops, and the air damper narrows, reducing air volume and pressure, and the gas valve assembly also narrows. If the heat continues to decrease and the fan reaches its minimum frequency but still cannot meet the demand, a pneumatic mechanism shuts down one combustion channel and the corresponding gas valve assembly, releasing excess air. If the heat requirement further decreases, this process continues until only one combustion channel remains. When the required heat increases again, the pneumatic mechanism acts in the opposite direction, opening combustion channels and corresponding gas valve assemblies sequentially until all combustion channels are open.
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First, the fan is turned on, allowing air to enter the burner from the lower part of the air damper. The air then enters the distribution chamber, which evenly distributes the air into each mixer. One gas valve assembly corresponding to one mixer is opened, allowing gas to enter that mixer. The air and gas inside the mixer mix at a predetermined air-fuel ratio to form the required premixed gas. Next, the premixed gas enters the premixing device for further mixing and ignites at the combustion channel's outlet to form a combustion surface. Once the flame stabilizes, the next gas valve assembly is opened. This process continues until all gas valve assemblies are opened, and stable flames form at the outlets of all combustion channels. Finally, the fan frequency and air damper opening are adjusted to control combustion intensity of the combustion surface.
The excess air ratio refers to the ration of the actual air supplied for fuel combustion to the theoretical amount of air required for complete combustion. It is an important parameter that reflects the fuel-to-air ratio. When the value is greater than 1, it indicates that the actual air supply exceeds the theoretical requirement, and the exceeding part is called surplus air or excess air. Excess air is carried away with exhaust gases, and a significant portion of it does not participate in heat exchange, leading to energy waste. Therefore, another key factor in evaluating a burner is ensuring a low excess air ratio.
The water-cooled premixed burner in this invention ensures more complete combustion by utilizing premixing while the water-cooling method reduces the combustion temperature (kept below 1400° C.). This approach ensures complete combustion while reducing nitrogen oxides (NOx) emissions in the exhaust gases. Additionally, the burner allows adjustment of the gas and air in the combustion channel according to user needs, achieving a low excess air ratio and reduced energy consumption.
In the diagrams, Diagram A represents all three combustion channels burning simultaneously, with a fixed fuel-to-air ratio and an oxygen content of 5% in the premixed gas. At this point, combustion is complete, nitrogen oxides (NOx) emissions are low, there is minimal excess air and low energy consumption. Diagram B shows the scenario where the gas valves of two combustion channels are closed, but their air outlets remain closed, leaving only one combustion channel active. In this case, the oxygen content in the premixed gas rises to 15.7%, resulting in higher excess air and increased energy consumption. Diagram C depicts the case where the gas valves of two combustion channels are closed, but their air outlets are opened, leaving one combustion channel active. Here, the oxygen content in the premixed gas is 5%, ensuring complete combustion while reducing nitrogen oxides (NOx) emissions in the exhaust gases. At the same time, the excess air ratio and energy consumption both remain low.
The beneficial effects of some embodiments of the present disclosure are:
Although embodiments have been described in language specific to structural features and/or methodological acts, it is to be understood that the disclosure is not necessarily limited to the specific features or acts described. Rather, the specific features and acts are disclosed as illustrative forms of implementing the embodiments. Conditional language, such as, among others, “can,” “could,” “might,” or “may,” unless specifically stated otherwise, or otherwise understood within the context as used, is generally intended to convey that certain embodiments could include, while other embodiments do not include, certain features, elements, and/or steps. Thus, such conditional language is not generally intended to imply that features, elements, and/or steps are in any way required for one or more embodiments or that one or more embodiments necessarily include logic for deciding, with or without user input or prompting, whether these features, elements, and/or steps are included or are to be performed in any particular embodiment.
| Number | Date | Country | Kind |
|---|---|---|---|
| 202311537796.X | Nov 2023 | CN | national |
