Biomass gas combustion system capable of accurately controlling combustion

Abstract

The utility model discloses a biomass gas combustion system capable of accurately controlling combustion. The system comprises a biomass gas burner, a biomass gas pipeline connected with the burner, an air blower, an air supply pipeline connected with the air blower and the burner, a tar collecting device in a hearth of the biomass boiler, an oxygen sensor arranged on a smoke exhaust pipeline of the boiler, a controller based on a PLC (Programmable Logic Controller) system, and an air blower frequency converter. Gas component, flow, temperature and pressure measuring devices are arranged on the biomass gas pipeline, and flow and temperature measuring devices are arranged on the air supply pipeline. The controller calculates the oxygen amount needed by biomass gas combustion and the oxygen amount provided by the air blower according to data fed back by the measuring device, and controls the air blower frequency converter to adjust the air amount of the air blower under correction of data fed back by the oxygen sensor on the boiler smoke exhaust pipeline, so that combustion is accurately controlled under the condition of partial load of the boiler, and the combustion efficiency is improved. The combustion efficiency is improved, and the pollutant emission is reduced.

Description

TECHNICAL FIELD

[0001] The utility model relates to the technical field of biomass gas combustor, more particularly to a biomass gas combustion system of accurate control combustion. BACKGROUND

[0002] Biomass gas is a combustible gas produced by biomass raw materials (wood chips, bamboo, rice husk, fruit shell and other agricultural and forestry waste) through high-temperature cracking of biomass gasifier. Biomass gas is a low-calorific value combustible gas that needs to be mixed with air at a suitable ratio to achieve complete combustion. The main way of biomass gas utilization at present is to supply biomass gas produced by biomass gasifier to biomass gas boiler for combustion and heat supply. The biomass gas boiler combustor is provided with a blower to send air into the combustor to mix with the biomass gas produced by the biomass gasifier and then burn.

[0003] In actual operation, the composition of the biomass gas produced by the biomass gasifier is unstable. At the same time, the biomass gasifier + biomass gas boiler heat supply system is affected by the user side demand and runs at partial load for a long time. Under the condition of partial load operation of the biomass gasifier, the biomass gas flow decreases, and compared with the full load condition, the gas composition also changes, so the air quantity cannot be simply adjusted in proportion to the reduction of the biomass gas flow. Therefore, the air quantity required for complete combustion of the biomass gas entering the biomass gas boiler combustor needs to be accurately controlled to ensure complete combustion of the biomass gas. The existing combustor controls the air-fuel ratio mainly by manual operation, relying on the experience of the operator to adjust the air quantity of the blower, which cannot ensure the optimal ratio of biomass gas to air in the combustor and cannot effectively monitor the combustion of biomass gas. Oxygen is often excessive, nitrogen oxide emission exceeds the standard, or oxygen is insufficient, and part of the biomass gas is not completely combusted and discharged, etc. This not only reduces the utilization rate of biomass gas, but also brings inconvenience to the operation and management of the system.

[0004] The biomass combustor with the patent number 201821890644 is provided with a carbon monoxide and oxygen concentration sensor on the tail gas pipe, judges the combustion condition of the biomass gas according to the feedback data of the sensor, and controls the gas supply valve of the biomass gas to adjust the ratio of the biomass gas to air, so as to improve the combustion efficiency of the biomass gas. However, this scheme does not consider the problem of control lag and untimely response of the gas supply valve in adjusting the biomass gas flow, so it is difficult to achieve the purpose of accurately controlling complete combustion of the biomass gas. UTILITY MODEL CONTENTS

[0005] Therefore, the utility model provides a biomass gas combustion system of accurate control combustion. The system can effectively solve the problem that the existing biomass gas combustor cannot accurately control combustion under the condition of partial load, improve the efficiency of the combustor, and also collect unburned tar back to the gasifier, further improving the efficiency of the whole gasification heat supply system.

[0006] In order to achieve the above object, the utility model adopts the following technical scheme:

[0007] A biomass gas combustion system of accurate control combustion, include: biomass gas combustor on biomass gas boiler body, with the biomass gas combustor connection's biomass gas pipeline, air blower, the air supply pipeline of connecting the air blower with the biomass gas combustor, the tar collection device of biomass gas boiler hearth inner bottom, set up on the boiler flue gas pipeline oxygen sensor, the controller based on PLC system, air blower frequency converter;

[0008] The controller is electrically connected with the air blower frequency converter and the oxygen sensor respectively;

[0009] The air blower frequency converter is electrically connected with the air blower.

[0010] Preferably, dust and coke filters, gas composition measuring devices, flow measuring devices A, pressure measuring devices and temperature measuring devices A are sequentially arranged on the biomass gas pipeline from the inlet end to the outlet end.

[0011] The gas composition measuring devices, flow measuring devices A, pressure measuring devices and temperature measuring devices A are electrically connected with the controller respectively.

[0012] Preferably, the pressure measuring devices are absolute pressure measuring devices.

[0013] Preferably, temperature measuring devices B and flow measuring devices B are arranged on the air inlet pipeline.

[0014] The temperature measuring devices B and flow measuring devices B are electrically connected with the controller respectively.

[0015] Preferably, the system further comprises tar level measuring devices, tar pumps and tar pipelines connecting the tar pumps and the tar collection devices.

[0016] The tar level measuring devices and the tar pumps are electrically connected with the controller respectively.

[0017] Preferably, the tar pumps are connected with biomass gasifiers in the external environment.

[0018] Compared with the prior art, the utility model has the following beneficial effects:

[0019] 1, the utility model discloses a biomass gas pipeline gas composition measuring device and flow measuring device A, air inlet pipeline temperature measuring device B and flow measuring device B, through signal feedback to controller, controller adjusts the frequency converter of air blower control air blower capacity, reaches the purpose of automatic accurate regulation, guarantees the combustion efficiency of combustor, reduces the nitrogen oxides emission in boiler flue gas,

[0020] 2, the utility model discloses the feedback data of oxygen sensor on boiler flue gas pipeline, eliminates the influence of excess air coefficient change under partial load condition, through oxygen sensor signal correction air blower capacity, reaches the purpose of accurate control of air-fuel ratio.

[0021] 3, the utility model discloses still reaches the purpose that the tar of incomplete combustion in biomass gas is collected and automatically returns gasification furnace and continues to use through the tar collection device in hearth, further improves the efficiency of whole system. DRAWINGS

[0022] In order to more clearly illustrate the technical scheme in the embodiment of the utility model or prior art, the following will be to the embodiment or prior art description needed to use the drawing briefly introduced, obviously, the drawing in the following description only is the embodiment of the utility model, for the ordinary skilled person in the art comes, under the premise of not paying creative labor, still can obtain other drawings according to the provided drawing.

[0023] Figure 1 It is the component diagram of the biomass gas combustion system of accurate control combustion of the utility model;

[0024] Figure 2 It is the schematic diagram of the biomass gas combustion system control method of accurate control combustion of the utility model;

[0025] Among them, in the drawing:

[0026] 1-biomass gas combustor;2-flow measuring device A;3-gas composition measuring device;4-removing tar and dust filter;5-biomass gas pipeline;-6-air blower frequency converter;7-air blower;8-temperature measuring device B;9-flow measuring device B;10-air supply pipeline;11-tar pump;12-tar pipeline;13-tar collection device;14-tar liquid level measuring device;15-oxygen sensor;16-boiler flue gas pipeline;17-biomass gas boiler;18-controller;19-pressure measuring device;20-temperature measuring device A. DETAILED DESCRIPTION

[0027] The technical solutions in the embodiments of the utility model will be clearly and completely described below with reference to the drawings in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, rather than all the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of the utility model.

[0028] Embodiment 1

[0029] The embodiment provides a biomass gas combustion system for precisely controlling combustion.

[0030] According to Figure 1 As shown in the figure, the biomass gas burner (1) is arranged on the biomass gas boiler (17) body, the biomass gas pipeline (5) is connected with the burner, the air blower (7) is arranged, the air inlet pipeline (10) is connected between the air blower (7) and the burner (1), the tar collecting device (13) is arranged in the biomass boiler hearth, the oxygen sensor (15) is arranged on the boiler exhaust pipeline (16), the controller (18) based on the PLC system, the air blower frequency converter (6) is arranged.

[0031] The dust and tar removal filter (4) is arranged on the biomass gas pipeline (5) in sequence, the gas component measuring device (3), the flow measuring device A (2), the pressure measuring device (19) and the temperature measuring device A (20) are arranged.

[0032] The dust and tar removal filter (4) is arranged on the biomass gas pipeline (5) in sequence, the gas component measuring device (3), the flow measuring device A (2), the pressure measuring device (19) and the temperature measuring device A (20) are arranged. The dust and tar removal filter (4) is arranged on the biomass gas pipeline (5) in sequence, the gas component measuring device (3), the flow measuring device A (2), the pressure measuring device (19) and the temperature measuring device A (20) are arranged.

[0033] The temperature measuring device B (8) and the flow measuring device B (9) are arranged on the air supply pipeline (10).

[0034] The temperature measuring device B (8) and the flow measuring device B (9) are arranged on the air supply pipeline (10).

[0035] The tar collecting device (13) comprises a tar liquid level measuring device (14) arranged on the tar collecting device, a tar pump (11) and a tar pipeline (12) connected between the tar pump and the tar collecting device.

[0036] The gas composition measuring device (3), the flow measuring device A (2), the pressure measuring device (19), and the temperature measuring device A (20) on the biomass gas pipeline (5) are electrically connected with the controller (18) based on the PLC system, for feeding back the volume fraction of the main combustible gases CO, H2, and CH4 in the biomass gas, the volume flow of the biomass gas, and the temperature and pressure signals of the biomass gas measured by the above sensors to the controller (18). The controller (18) analyzes the above data, and the partial pressure and temperature of the main combustible gases CO, H2, and CH4 can be obtained from the temperature, pressure, and volume fraction of the main combustible gases CO, H2, and CH4 in the biomass gas; the mass flow of each main combustible gas CO, H2, and CH4 can be obtained from the partial pressure, temperature, and volume flow of the main combustible gases CO, H2, and CH4; the mass flow of oxygen required to ensure complete combustion of the main combustible gases CO, H2, and CH4 in the biomass gas can be obtained from the chemical reaction formula; and the controller can obtain the actual mass flow of oxygen required to ensure complete combustion of the main combustible gases CO, H2, and CH4 in the biomass gas after correction by the excess air coefficient.

[0037] The temperature measuring device B (8) and the flow measuring device B (9) on the air supply pipeline are electrically connected with the controller (18) based on the PLC system, for feeding back the temperature and volume flow of the air entering the combustor (1) measured by the above sensors to the controller (18). The controller can obtain the mass flow of oxygen provided by the air blower (7) in real time according to the above data.

[0038] The tar level measuring device (14) on the tar collecting device (13) is electrically connected with the controller (18) based on the PLC system, for feeding back the liquid level signal of the unburned tar in the hearth collected by the tar collecting device (13) to the controller (18).

[0039] The oxygen sensor (15) on the boiler flue gas pipeline (16) is electrically connected with the controller (18) based on the PLC system, for feeding back the oxygen concentration signal in the flue gas after combustion to the controller (18).

[0040] The air blower frequency converter (6) is electrically connected with the controller (18) based on the PLC system, and the air blower frequency converter (6) is electrically connected with the air blower (7). The controller (18) can control the amount of air entering the combustor (1) by the air blower frequency converter (6).

[0041] Example 2

[0042] The embodiment provides a control method of a biomass gas combustion system for precisely controlling combustion, which comprises the following steps:

[0043] Step (1): The controller obtains the theoretical oxygen mass flow required for complete combustion of the biomass gas according to the feedback data of the gas composition measuring device (3), flow measuring device A (2), pressure measuring device (19), and temperature measuring device A (20) on the biomass gas pipeline (5), and obtains the mass flow of oxygen required for combustion by correcting the preset excess air factor.

[0044] Step (2): The controller (8) obtains the real-time oxygen mass flow provided by the air blower (7) according to the feedback data of the temperature measuring device B (8) and the flow measuring device B (9) on the air supply pipeline (10).

[0045] Step (3): The controller (18) adjusts the air volume of the air blower (7) by the frequency converter (6) according to the difference between the oxygen mass flow obtained in steps (1) and (2).

[0046] Step (4): The controller (18) adjusts the air volume of the air blower (7) in real time through the feedback data of the oxygen sensor (15) arranged on the boiler flue gas pipeline (16), to ensure accurate control of the complete combustion of the biomass gas.

[0047] Step (5): When the tar level sensor (14) on the tar collecting device (13) in the furnace detects that the tar level reaches the set value, the tar level signal is fed back to the controller (18), and the controller (18) starts the tar pump (11) to return the collected tar in the furnace to the gasifier pyrolysis combustion, further improving the efficiency of the entire system.

[0048] The feedback signals of the gas composition measuring device (3), flow measuring device A (2), pressure measuring device (19), and temperature measuring device A (20) on the biomass gas pipeline (5) in step (1) are calculated and analyzed in the controller (18) to obtain the oxygen mass flow required for combustion of the biomass gas as follows:

[0049] The oxygen mass flow required for complete combustion of the main combustible gases CO, H2, and CH4 in the biomass gas is:

[0050] Q O1 = λ × ∑ (VOL i × P × M i ) / (R × (T a + 273.15) × 1000) × Q1 × θ i

[0051] In the formula:

[0052] Q O1 is the oxygen mass flow required for complete combustion of the combustible gases in the biomass gas (kg / h);

[0053] VOL i The volume fraction (%) of the corresponding combustible gas measured by the gas component measuring device;

[0054] P is the absolute pressure (Pa) of the biomass gas measured by the pressure measuring device on the biomass gas pipeline;

[0055] M i The molar mass of the corresponding combustible gas (CO is 28 g / mol, H2 is 2 g / mol, CH4 is 16 g / mol);

[0056] R is the gas constant 8.314;

[0057] T a The biomass gas temperature (℃) measured by the temperature measuring device A on the biomass gas pipeline;

[0058] Q1 is the biomass gas volume flow rate (m 3 / h) measured by the flow rate measuring device A;

[0059] θ i The oxygen consumption coefficient of the corresponding combustible gas combustion (CO is 0.57, H2 is 8, CH4 is 4);

[0060] λ is the excess air coefficient;

[0061] i is the combustible gas CO, H2, CH4 in the biomass gas;

[0062] Wherein the feedback signals of the flow rate measuring device B (9) and the temperature measuring device B (8) on the air supply pipeline (10) are calculated and analyzed in the controller (18) to obtain the process of the oxygen mass flow rate provided by the air blower (7) in real time as follows:

[0063] Q O2 =(6.72×P a ) / (R×(T b +273.15)×1000)×Q2

[0064] In the formula:

[0065] Q O2 The oxygen mass flow rate (kg / h) provided by the air blower (7) in real time;

[0066] P a The atmospheric pressure (Pa);

[0067] R is the gas constant 8.314;

[0068] T b The air temperature (℃) measured by the temperature measuring device B (8) on the air supply pipeline (10);

[0069] Q2 is the volumetric flow rate (m³ / s) of the air supplied by the blower (7) as measured by the flow measurement device B (9). 3 / h);

[0070] The control principle of step (3) controller (8) adjusting blower (7) is as follows:

[0071] When Q O1 >Q O2 When Q is reached, the controller (18) increases the air volume of the blower (7) through the frequency converter (6); when Q is reached... O1 <Q O2 When Q is reached, the controller (18) reduces the air volume of the blower (7) through the frequency converter (6); when Q is reached... O1 =Q O2 When the controller (18) does not operate.

[0072] In step (4), the oxygen sensor (15) on the boiler flue gas duct (16) feeds back the oxygen concentration signal in the flue gas after combustion to the controller (18). The controller (18) compares the oxygen concentration in the boiler flue gas with the set oxygen concentration to determine whether the mixing ratio of biomass gas and air meets the requirements for complete combustion. Based on the comparison deviation, the air volume of the blower (7) is corrected to achieve the purpose of precise combustion control.

[0073] In step (5), the tar level measuring device (14) on the tar collection device (13) feeds back the liquid level signal of the unburned tar collected in the furnace to the controller (18). When the set high limit of tar liquid level is reached, the tar pump (11) is started to return the collected tar in the furnace to the gasifier for pyrolysis and combustion. When the set low limit of tar liquid level is reached, the tar pump (11) is stopped, and the tar collection device (13) continues to collect the unburned tar in the furnace.

[0074] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to the method section.

[0075] The above description of the disclosed embodiments enables those skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those 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 is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A biomass gas combustion system for precise control of combustion, characterized by, The application relates to a biomass gas combustion boiler, which comprises the following parts: a biomass gas burner on a biomass gas boiler body, a biomass gas pipeline connected with the biomass gas burner, a blower, an air supply pipeline connecting the blower and the biomass gas burner, a tar collecting device on the bottom of a biomass gas boiler hearth, an oxygen sensor arranged on a boiler exhaust pipeline, a PLC system-based controller, and a blower frequency converter; the controller is electrically connected with the blower frequency converter and the oxygen sensor respectively; the blower frequency converter is electrically connected with the blower.

2. The precisely controlled combustion biomass gas combustion system according to claim 1, wherein, a dust and coke removing filter, a gas component measuring device, a flow measuring device A, a pressure measuring device and a temperature measuring device A are sequentially arranged on the biomass gas pipeline from an inlet end to an outlet end; the gas component measuring device, the flow measuring device A, the pressure measuring device and the temperature measuring device A are electrically connected with the controller respectively.

3. The precisely controlled combustion biomass gas combustion system of claim 2, wherein, the pressure measuring device is an absolute pressure measuring device.

4. The precisely controlled combustion biomass gas combustion system of claim 3, wherein, a temperature measuring device B and a flow measuring device B are arranged on the air supply pipeline; the temperature measuring device B and the flow measuring device B are electrically connected with the controller respectively.

5. The precisely controlled combustion biomass gas combustion system according to claim 4, wherein, The application further comprises the following parts: a tar liquid level measuring device, a tar pump and a tar pipeline connecting the tar pump and the tar collecting device; the tar liquid level measuring device and the tar pump are electrically connected with the controller respectively.

6. The precisely controlled combustion biomass gas combustion system according to claim 5, wherein, the tar pump is connected with an external biomass gasifier.

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