Low pressure boiler combustion experiment platform

Abstract

The application discloses a low-pressure boiler combustion experiment platform and belongs to the technical field of gas boilers. The low-pressure boiler combustion experiment platform is provided with an air inlet system, a furnace body and a flue gas pipeline. The air inlet system is connected with the furnace body and comprises a nitrogen supply device, an oxygen supply device and a methane supply device. The bottom of the internal hearth of the furnace body is communicated with the burner, and the top end of the hearth is provided with a radiation type heat flow meter. The flue gas pipeline is provided with a pressure detection device and a temperature detection device. The outlet end of the flue gas pipeline is divided into two paths via a first bifurcated pipeline. One path is connected with a first vacuum pump and a flue gas analyzer, and the other path is connected with a second vacuum pump. The low-pressure boiler combustion experiment platform can simulate low-pressure conditions to carry out gas boiler combustion experiments. The influence of oxygen content and equivalence ratio changes on the combustion characteristics, flue gas heat transfer and flame shape in the actual boiler operation under low-pressure conditions is studied.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of gas boiler technology, in particular to a low-pressure boiler combustion experiment platform. BACKGROUND

[0002] The gas boiler under low-pressure conditions often has problems such as insufficient output, reduced combustion efficiency, and high exhaust gas temperature. At present, the specific change process of heat transfer characteristics and combustion reaction under low-pressure conditions is not well understood. The existing knowledge and experience cannot accurately predict the influence of reduced pressure on the combustion characteristics such as the combustion time, ignition temperature, and burnout rate in the boiler.

[0003] The unique geographical factors of plateau regions create environmental conditions such as low pressure and low oxygen content. For every 1000 meters of altitude increase, atmospheric pressure decreases by about 10 kPa, air density decreases by about 0.1 kg / m 3 , and oxygen content decreases by about 0.3 kg / m 3 . This leads to a series of problems such as reduced boiler efficiency and insufficient output when the boiler operates in plateau regions. The main response of mainstream boiler manufacturers is to choose a larger output boiler or to design and modify the boiler based on subjective experience, lacking sufficient scientific guidance and standardized design and manufacturing processes. At present, there are a large number of gas boilers operating in important plateau regions and cities. These boilers still follow the design and operation reference standards of boilers in plain regions. Practice has proven that the current standards cannot well design and operate boilers in plateau environments. Overall, there is little research on gas boilers under low-pressure and low-oxygen content conditions in China, so it is of great significance and value to design a low-pressure boiler combustion experiment platform to simulate various boiler experiments. SUMMARY

[0004] The purpose of the present application is to overcome the problems in the prior art and provide a low-pressure boiler combustion experiment platform.

[0005] The present application provides a low-pressure boiler combustion experiment platform, which comprises: an air intake system comprising a nitrogen supply device, an oxygen supply device, and a methane supply device, all of which are connected to a burner;

[0006] A furnace body, the bottom of the internal hearth of which is in communication with the burner, and the top of the hearth is provided with a radiation type heat flow meter; the top of the hearth is also provided with a flue gas pipeline, which is provided with a pressure detection device and a temperature detection device, and the outlet end of the flue gas pipeline is divided into two paths via a first bifurcated pipeline, one path is connected to a first vacuum pump and a flue gas analyzer, and the other path is connected to a second vacuum pump.

[0007] Preferably, the output end of the nitrogen supply device is also connected with a first mass flow controller; the output end of the oxygen supply device is also connected with a second mass flow controller; and the output end of the methane supply device is also connected with a third mass flow controller.

[0008] Preferably, the first mass flow controller and the second mass flow controller are connected with a fourth mass flow controller through a mixing pipeline, the fourth mass flow controller is connected with the burner through two paths of a second bifurcated pipeline, a first screw valve and a second screw valve are arranged on the second bifurcated pipeline respectively, the third mass flow controller is connected with an inner tube of the burner through a first pipeline, and a third screw valve is arranged on the first pipeline.

[0009] Preferably, a high-speed camera is further included for collecting complete flame images.

[0010] Preferably, a thermocouple array is further included, and the thermocouple array includes a plurality of thermocouples arranged along the length direction of the furnace.

[0011] Preferably, the furnace body is a tubular furnace.

[0012] The second object of the present application is to provide a method for carrying out experiments by using the low-pressure boiler combustion experiment platform.

[0013] S1, starting to preheat the hearth of the furnace body, heating the wall temperature of the hearth to 300-350 DEG C;

[0014] S2, opening the nitrogen supply device and the oxygen supply device, adjusting the ratio of nitrogen and oxygen through the first mass flow controller and the second mass flow controller on the mixing pipeline to change the oxygen content of the combustion air of the gas; controlling the air to enter the outer tube of the burner to simulate the combustion state of the diffusion flame, and controlling the air to enter the inner tube of the burner to simulate the combustion state of the premixed flame; and introducing air into the hearth to remove the residual combustible gas in the hearth;

[0015] S3, opening the methane supply device, controlling the mass flow of methane and air through the third mass flow controller and the fourth mass flow controller to adjust different equivalence ratios, and igniting in the hearth;

[0016] S4, starting the first vacuum pump and the second vacuum pump to adjust different furnace pressures, and arranging a pressure detection device on the smoke exhaust pipeline to detect the pressure in the hearth, and waiting until the furnace pressure is stable;

[0017] S5, after the combustion in the furnace is stable, collecting complete flame images in real time through the front opening of the furnace body, and transmitting the collected flame images to the control center;

[0018] S6, detecting the temperature in the hearth to obtain a complete internal temperature field of the hearth;

[0019] S7. Measure the radiant heat flux density inside the furnace using a radiant heat flow meter at the top of the furnace.

[0020] S8. Connect the furnace outlet pipe to the temperature detection device, and connect the sampling gun to the flue gas analyzer to measure the furnace outlet flue gas temperature and flue gas component distribution.

[0021] S9. Repeat the above steps and collect experimental data under different working conditions.

[0022] Preferably, the acquisition of complete flame images is achieved using a high-speed camera. During the experiment, the integration time and sampling frame rate of the high-speed camera are continuously tested and adjusted to determine the acquisition process, and the acquired images are transmitted to the control center.

[0023] Compared with existing technologies, the beneficial effects of this invention are: the low-pressure boiler combustion experimental platform of this invention can simulate low-pressure conditions to conduct combustion experiments on gas-fired boilers. It studies the effects of changes in oxygen content and equivalence ratio under low-pressure conditions on the combustion characteristics, flue gas heat transfer, and flame morphology of actual boilers during operation. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the structure of the present invention. Detailed Implementation

[0025] The following is in conjunction with the appendix Figure 1 The specific embodiments of the present invention will be described in detail below, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0026] This embodiment of a low-pressure boiler combustion test platform includes: an air intake system, including a nitrogen supply device 1, an oxygen supply device 2 and a methane supply device 3, wherein the nitrogen supply device 1, the oxygen supply device 2 and the methane supply device 3 are all connected to the burner 11.

[0027] The furnace body 12 has a furnace chamber 15 whose bottom is connected to the burner 11. A radiation heat flow meter 14 is installed at the top of the furnace chamber 15. A flue gas pipe is also provided at the top of the furnace chamber 15. A pressure detection device 18 and a temperature detection device 19 are installed on the flue gas pipe. The outlet end of the flue gas pipe is divided into two paths via a first branch pipe. One path is connected to the first vacuum pump 20 and the flue gas analyzer 21, and the other path is connected to the second vacuum pump 22.

[0028] As a preferred mode, the output end of the nitrogen supply device 1 is also connected with a first mass flow controller 4; the output end of the oxygen supply device 2 is also connected with a second mass flow controller 5; and the output end of the methane supply device 3 is also connected with a third mass flow controller 6.

[0029] As a preferred mode, the first mass flow controller 4 and the second mass flow controller 5 are connected with a fourth mass flow controller 7 through a mixing pipeline, the fourth mass flow controller 7 is connected with the burner 11 through a second bifurcated pipeline, the first screw valve 8 and the second screw valve 9 are respectively arranged on the second bifurcated pipeline, the third mass flow controller 6 is connected with the inner tube of the burner 11 through a first pipeline, and the third screw valve 10 is arranged on the first pipeline.

[0030] As a preferred mode, a high-speed camera 16 is further included for collecting complete flame images.

[0031] As a preferred mode, a thermocouple array 13 is further included, and the thermocouple array 13 includes a plurality of thermocouples arranged along the length direction of the furnace.

[0032] As a preferred mode, the furnace body 12 is a tubular furnace.

[0033] The above-mentioned low-pressure boiler combustion experiment platform carries out the experiment by the following method, which includes the following steps:

[0034] S1, starting the furnace body 12 to preheat the hearth 15, and heating the wall temperature of the hearth 15 to 300-350℃;

[0035] S2, opening the nitrogen supply device 1 and the oxygen supply device 2, adjusting the oxygen content of the gas companion air by the first mass flow controller 4 and the second mass flow controller 5 on the mixing pipeline, simulating the combustion state of the diffusion flame by controlling the air entering the outer tube of the burner 11, simulating the combustion state of the premixed flame by controlling the air entering the inner tube of the burner 11, and introducing air into the hearth 15 to remove the residual combustible gas in the hearth 15;

[0036] S3, opening the methane supply device 3, adjusting different equivalence ratios by controlling the mass flow of the methane and the air through the third mass flow controller 6 and the fourth mass flow controller 7, and igniting in the hearth 15;

[0037] S4, starting the first vacuum pump 20 and the second vacuum pump 22 to adjust different furnace pressures, detecting the pressure in the hearth 15 by the pressure detection device 18 arranged on the smoke pipeline, and waiting for the stable furnace pressure;

[0038] S5, after the stable combustion in the furnace, collecting complete flame images in real time through the front opening of the furnace body, and transmitting the collected flame images to the control center;

[0039] S6, temperature detection is performed on the furnace 15 to obtain a complete internal temperature field of the furnace;

[0040] S7, the radiant heat flux density in the furnace 15 is measured by the radiant heat flow meter 14 on the top of the furnace;

[0041] S8, the furnace 15 outlet pipeline is connected to the temperature detection device 19, and the sampling gun is connected to the flue gas analyzer 21 to measure the flue gas temperature at the furnace outlet and the flue gas component distribution;

[0042] S9, the above steps are repeated to count the experimental data under different working conditions.

[0043] As a preferred mode, the collection of complete flame images uses the high-speed camera 16, the integral time and sampling frame rate of the high-speed camera 16 are continuously tested and adjusted during the experiment, and the collected images are transmitted to the control center.

[0044] The low-pressure boiler combustion experiment platform provided in the embodiment includes a nitrogen supply device 1, an oxygen supply device 2, a methane supply device 3, a first mass flow controller 4, a second mass flow controller 5, a third mass flow controller 6, a fourth mass flow controller 7, a first screw valve 8, a second screw valve 9, a third screw valve 10, a burner 11, a furnace body 12, a thermocouple array 13, a radiant heat flow meter 14, a furnace 15, a high-speed camera 16, a computer 17, a pressure detection device 18, a temperature detection device 19, a first vacuum pump 20, a flue gas analyzer 21, and a second vacuum pump 22. Figure 1 The nitrogen cylinder 1 is connected to the first mass flow controller 4 through a pipeline, the oxygen cylinder 2 is connected to the second mass flow controller 5 through a pipeline, the first mass flow controller 4 and the second mass flow controller 5 are connected to the fourth mass flow controller 7 through a mixing pipeline, the fourth mass flow controller 7 is connected to two pipelines, one pipeline sends air into the outer pipe of the burner 11, and the other pipeline sends air into the inner pipe of the burner 11, the first screw valve 8 and the second screw valve 9 are arranged on the two pipelines, respectively. The methane cylinder is connected to the third mass flow controller 6 and the third screw valve 10 through a pipeline to send methane into the inner pipe of the burner 11. One end of the burner 11 is connected to the gas pipeline, and the other end is connected to the furnace 15. The furnace 15 is provided with the thermocouple array 13 and the radiant heat flow meter 14 on the top. The furnace 15 outlet is connected to the pressure gauge 18 and the thermometer 19 through a pipeline, and then is divided into two paths through a bifurcated pipeline, one path is connected to the first vacuum pump 20 and the flue gas analyzer 21, and the other path is connected to the second vacuum pump 22. The outer side of the furnace 15 is provided with the tubular furnace 12, and the outer side of the tubular furnace 12 is provided with the high-speed camera 16 and the computer 17.

[0045] The application discloses a mobile experimental platform device for a small-sized gas boiler under plateau conditions.

[0046] 1), start the tubular furnace 12 to preheat the hearth, heat the hearth wall temperature to 300 DEG C;

[0047] 2), open the pressure regulating valves on the nitrogen cylinder 1 and the oxygen cylinder 2, adjust the oxygen content of the air flow accompanying gas by adjusting the ratio of nitrogen and oxygen through the first mass flow controller 4 and the second mass flow controller 5 on the pipeline, control the air entering the burner 11 outer pipe to simulate the combustion state of the diffusion flame through the first screw valve 8 and the second screw valve 9 on the pipeline, and control the air entering the burner 11 inner pipe to simulate the combustion state of the premixed flame, and introduce air into the hearth 15 for several minutes to remove the combustible gas possibly remaining in the hearth 15;

[0048] 3), open the pressure regulating valve on the methane cylinder 3, control the mass flow of methane and air through the third mass flow controller 6 and the fourth mass flow controller 7 on the pipeline to adjust different equivalence ratios, and ignite in the hearth 15;

[0049] 4), start the first vacuum pump 20 and the second vacuum pump 22 to adjust different furnace pressures through the air exhaust pipeline, and the pipeline is provided with a pressure gauge 18 for detecting the pressure in the hearth 15 in real time;

[0050] 5), after the combustion in the furnace is stable, the complete flame image is collected through the front opening of the tubular furnace by using a high-speed camera 16, the integral time and the sampling frame rate of the high-speed camera are continuously tested and adjusted during the experiment, and the data are transmitted to a computer 17 through a data line;

[0051] 6), the thermocouple array 13 on the top of the hearth is driven by a motor to extend into the hearth 15 to measure the temperature, and the complete internal temperature field of the hearth is measured by changing the insertion position and length of the thermocouple array 13;

[0052] 7), the radiant heat flow meter 14 on the top of the hearth is used to measure the radiant heat flux density in the hearth 15;

[0053] 8), the outlet pipeline of the hearth 15 is connected with a thermometer 19, and a sampling gun is connected with a flue gas analyzer 21, so that the flue gas temperature at the hearth outlet and the flue gas component distribution are measured;

[0054] 9), the above steps are repeated to count the experimental data under different working conditions. Specifically, the influence of different gas pressures 90.0 kPa, 79.2 kPa, 70.1 kPa and 61.1 kPa, different oxygen mass fractions 0.233, 0.200 and 0.170 and different equivalence ratios 0.6, 0.8, 1.0, 1.2 on the combustion characteristics, flue gas heat transfer and flame shape can be studied.

[0055] While embodiments of the application have been shown and described, it is to be understood that the embodiments described are merely exemplary of the principles and application of the present application. Numerous modifications and adaptions can be made without departing from the spirit and scope of the present application, which is defined by the following claims and their equivalents.

Claims

1. A low pressure boiler combustion test platform, characterized in that, The utility model relates to a low pressure boiler combustion experiment platform, which comprises: An air intake system comprising a nitrogen supply device (1), an oxygen supply device (2), and a methane supply device (3), all of which are connected to a burner (11); A furnace body (12) having an internal hearth (15) with a bottom communicating with the burner (11), and a top end provided with a radiation type heat flow meter (14); the hearth (15) further has a flue gas pipeline provided with a pressure detection device (18) and a temperature detection device (19), and the outlet end of the flue gas pipeline is divided into two paths via a first bifurcated pipeline, one of which is connected to a first vacuum pump (20) and a flue gas analyzer (21), and the other of which is connected to a second vacuum pump (22); The output end of the nitrogen supply device (1) is further connected to a first mass flow controller (4); the output end of the oxygen supply device (2) is further connected to a second mass flow controller (5); and the output end of the methane supply device (3) is further connected to a third mass flow controller (6); The first mass flow controller (4) and the second mass flow controller (5) are connected to a fourth mass flow controller (7) via a mixing pipeline, the fourth mass flow controller (7) is divided into two paths via a second bifurcated pipeline to communicate with the inner tube and the outer tube of the burner (11), respectively, and the second bifurcated pipeline is respectively provided with a first screw valve (8) and a second screw valve (9); the third mass flow controller (6) is connected to the inner tube of the burner (11) via a first pipeline, and the first pipeline is provided with a third screw valve (10); The platform further comprises a high-speed camera (16) for capturing complete flame images; The platform further comprises a thermocouple array (13) comprising a plurality of thermocouples arranged along the furnace length direction; The nitrogen and oxygen mixed gas simulates air, the oxygen content of the gas companion flow air is changed by adjusting the ratio of nitrogen and oxygen through the first mass flow controller (4) and the second mass flow controller (5); the air entering the outer tube of the burner (11) simulates the combustion state of a diffusion flame, and the air entering the inner tube of the burner (11) simulates the combustion state of a premixed flame; the mass flow of methane and air is controlled through the third mass flow controller (6) and the fourth mass flow controller (7) to adjust different equivalence ratios; The method for carrying out experiments by using the above low pressure boiler combustion experiment platform comprises the following steps: S1, start the furnace body (12) to preheat the hearth (15), and heat the wall temperature of the hearth (15) to 300-350 ℃; S2, open the nitrogen supply device (1) and the oxygen supply device (2), change the oxygen content of the gas companion flow air by adjusting the ratio of nitrogen and oxygen through the first mass flow controller (4) and the second mass flow controller (5); simulate the combustion state of a diffusion flame by controlling the air entering the outer tube of the burner (11), and simulate the combustion state of a premixed flame by controlling the air entering the inner tube of the burner (11); introduce air into the hearth (15) to remove the combustible gas remaining in the hearth (15); S3, open the methane supply device (3), control the mass flow of methane and air by the third mass flow controller (6) and the fourth mass flow controller (7) to adjust different equivalence ratios, and ignite in the furnace (15); S4, start the first vacuum pump (20) and the second vacuum pump (22) to adjust different furnace pressures, and set a pressure detection device (18) on the exhaust pipe to detect the pressure in the furnace (15), and wait for the furnace pressure to stabilize; S5, after the combustion in the furnace is stable, real-time complete flame images are collected through the front opening of the furnace body (12), and the collected flame images are transmitted to the control center; S6, the temperature in the furnace (15) is detected to obtain a complete internal temperature field of the furnace; S7, the radiant heat flow meter (14) at the top of the furnace measures the radiant heat flux density in the furnace (15); S8, the outlet pipe of the furnace (15) is connected with a temperature detection device (19), and a sampling gun is connected with a flue gas analyzer (21) to measure the flue gas temperature and the flue gas component distribution at the outlet of the furnace (15); S9, repeat the above steps to count the experimental data under different working conditions.

2. The low-pressure boiler combustion test platform of claim 1, wherein, The furnace body (12) is a tubular furnace.

3. The low-pressure boiler combustion test platform of claim 1, wherein, The collection of complete flame images uses a high-speed camera (16), the integration time and the sampling frame rate of the high-speed camera (16) are determined by continuous testing and adjustment during the experiment, and the collected images are transmitted to the control center.

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