Control method of high-precision and high-efficiency biomass gas-carbon co-production system

Abstract

The invention relates to the technical field of biomass gasification control, in particular to a high-precision and high-efficiency control method of a biomass gas-carbon co-production system, which comprises the following steps: constructing a three-level PID (Proportion Integration Differentiation) control ring of the biomass gas-carbon co-production system, the three-level PID control ring comprises an upper-layer control ring, a lower-layer control ring and a fuel gas control ring; the feeding amount of the gasifier is adaptively adjusted based on the upper-layer control ring; adaptively adjusting the air volume of the gasifier blower based on the lower-layer control ring; and based on the fuel gas control ring, the air induction amount of the gasifier induced draft fan is adaptively adjusted. According to the invention, the temperatures of the upper layer and the lower layer in the furnace body can be subjected to zoned control, so that the temperature in the gasification furnace is in an optimal gasification state, the gas production quality is adjusted, and the gas production stability and the gasification efficiency of the gasification furnace are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of biomass gasification control, and more particularly to a control method for a high-precision and high-efficiency biomass gas-char cogeneration system. Background Art

[0002] At present, in the process of biomass gasification, due to the variability of raw material characteristics (including differences in moisture content, particle size, type, dust content, etc.) and gasification reaction conditions (temperature, pressure, flow, air intake, and air output), it is difficult to achieve gas-carbon cogeneration control, resulting in low efficiency of gasifiers. When users use low amounts of gas, the low efficiency of gasifiers causes serious waste of raw materials. Traditional control methods often cannot adapt to these changes in time when gas is produced inefficiently, resulting in unstable gas quality, the generation of a large amount of impurities such as tar, affecting subsequent utilization, and serious energy waste.

[0003] Therefore, how to improve gas production stability and gasification efficiency is an urgent problem to be solved by those skilled in the art. Summary of the invention

[0004] In view of this, the present invention provides a high-precision and high-efficiency control method for a biomass gas-char cogeneration system, which can improve the gas production stability of a gasifier and improve the gasification efficiency.

[0005] In order to achieve the above object, the present invention adopts the following technical solution:

[0006] A high-precision and high-efficiency control method for a biomass gas-char cogeneration system, comprising:

[0007] Constructing a three-level PID control loop for a biomass gas-char cogeneration system, wherein the three-level PID control loop includes an upper control loop, a lower control loop and a gas control loop;

[0008] Adaptively adjusting the feed amount of the gasifier based on the upper control loop;

[0009] Adaptively adjusting the air volume of the gasifier blower based on the lower control loop;

[0010] The induced air volume of the induced draft fan of the gasifier is adaptively adjusted based on the fuel gas control loop.

[0011] Furthermore, the biomass gas-char cogeneration system includes: a first loader, a second loader, a buffer silo, a tower grate, a gasifier blower and a gas induced draft fan; a plurality of temperature transmitters are installed from top to bottom inside the gasifier; level meters are installed in the buffer silo and on the top of the gasifier;

[0012] The first loader is used to lift the material in the silo into the buffer silo;

[0013] The second loader is used to drive the material in the buffer silo into the gasifier;

[0014] The gasifier blower is used to provide oxygen for the reaction in the gasifier, and a blower flow meter is installed on the pipeline between the gasifier blower and the gasifier;

[0015] The gas induced draft fan is used to extract the gas in the gasifier; a temperature transmitter is installed on the gas pipeline between the input end of the gas induced draft fan and the gasifier; a gas flow meter, a gas pressure transmitter and an oxygen analyzer are installed on the gas pipeline between the output end of the gas induced draft fan and the gas-using equipment.

[0016] Further, the upper control loop includes an upper main regulator and an upper sub regulator;

[0017] The upper main regulator performs PID calculation according to the target value of the upper control temperature of the gasifier and the actual temperature value collected by the upper temperature sensor in the gasifier to obtain the result a;

[0018] The upper sub-regulator performs the following calculation based on the result a, the feedback value b of the oxygen content in the gasifier, and the coefficients k1 and k2: k1*a-K2*b, converts the calculation result into a height control value of the material, and controls the action of the feed motor based on the height control value;

[0019] If the actual temperature value collected by the upper temperature transmitter in the gasifier is less than the target value of the upper control temperature, the result a of the upper main regulator operation decreases, and the height control value also decreases accordingly. At this time, the upper auxiliary regulator controls the feed motor to reduce the feed speed;

[0020] If the actual temperature value collected by the upper temperature transmitter in the gasifier is greater than the target value of the upper control temperature, the calculation result a of the upper main regulator increases, and the height control value also increases accordingly. At this time, the upper auxiliary regulator controls the feed motor to increase the feed speed;

[0021] If the feedback value b of the oxygen content in the gasifier increases, the upper sub-regulator controls the feed motor to reduce the feed speed.

[0022] Furthermore, the material height in the gasifier is fed back to the upper sub-regulator in real time, and the material height in the gasifier is maintained between 8.7 meters and 10.7 meters by controlling the action of the feed motor. Within this material height range, the upper temperature of the gasifier is maintained between 95°C and 145°C.

[0023] Further, the lower control loop includes a lower main regulator and a lower sub regulator;

[0024] The lower layer main regulator performs PID calculation according to the target value of the lower layer control temperature of the gasifier and the actual temperature value collected by the lower layer temperature sensor in the gasifier to obtain the result A;

[0025] The lower layer sub-regulator performs the following calculation based on the result A, the lower layer pressure value B in the gasifier and the coefficients K3 and K4: K3*A-k4*B, converts the calculation result into an air volume control value, and controls the action of the gasifier blower based on the air volume control value;

[0026] If the actual temperature value collected by the lower temperature sensor in the gasifier is less than the target value of the lower control temperature, the result A of the lower main regulator operation increases, and the air volume control value also increases accordingly. At this time, the lower auxiliary regulator controls the gasifier blower to increase the air volume;

[0027] If the actual temperature value collected by the lower temperature sensor in the gasifier is greater than the target value of the lower control temperature, the result A of the lower main regulator operation decreases, and the air volume control value also decreases accordingly. At this time, the lower sub-regulator controls the gasifier blower to reduce the air volume.

[0028] Furthermore, the air volume of the gasifier blower is fed back to the lower sub-regulator in real time, and the air volume of the gasifier blower is maintained at 1100m 3 / h-5700m 3 / h range, within this air supply volume range, the temperature of the lower layer of the gasifier is maintained between 920℃-1370℃.

[0029] Furthermore, the amount of induced air of the gasifier blower controls the consumption of materials, and its expression is:

[0030] Material consumption D = amount of air entering the furnace AFR / (theoretical amount of air for complete combustion of designed raw materials V0*air equivalent ratio ε).

[0031] Further, the gas control loop includes a gas main regulator and a gas sub-regulator;

[0032] The gas main regulator calculates the following value based on the gas volume input value Z of the gas-using equipment, the actual temperature value T1 collected by the lower temperature sensor in the gasifier, and the coefficients K5 and K6: K5*Z+k6*T1, and converts the calculation result into the gas flow value A1;

[0033] The gas auxiliary regulator calculates K7*A1-k8*B1 according to the gas flow value A1, the gasifier upper pressure value B1 and the coefficients K7 and K8, converts the calculation result into a pressure control value, and controls the action of the gasifier induced draft fan according to the pressure control value.

[0034] Furthermore, the pressure in the gas pipeline is fed back to the gas auxiliary regulator in real time, and the pressure of the gas pipeline is maintained between 9kpa-20kpa and the gas flow rate is maintained at 4000m 3 / h-8000m 3 / h.

[0035] Furthermore, a temperature transmitter is installed at the grate position of the gasifier, which is used to detect the temperature of the ash in the furnace body; by setting the ash discharge temperature, the switching of the gas production and carbon production working modes of the gasifier is realized. When a large amount of gas is required, the ash discharge temperature is set to 710°C to slow down the slag discharge speed of the grate; when the gas demand decreases, the ash discharge temperature is set to 912°C to speed up the slag discharge speed of the grate.

[0036] It can be seen from the above technical solutions that, compared with the prior art, the present invention has the following beneficial effects:

[0037] The present invention constructs a three-stage PID control loop, so that the upper and lower temperatures in the furnace body can be controlled in a zoned manner, and the gas flow rate can be controlled, as well as the gasification furnace for gas-charcoal cogeneration control, thereby achieving more refined and higher-precision control of the gasification furnace, so that the temperature in the updraft gasification furnace is in the optimal gasification state, and the oxygen content in the fuel gas is minimized. The thickness of the material layer and the temperature in the upper furnace can be adjusted to effectively remove a large amount of tar, so that the biomass gas-charcoal cogeneration system is more stable and more robust. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0039] Figure 1 A schematic diagram of the structure of the biomass gas-charcoal cogeneration system provided by the present invention;

[0040] Figure 2 This is a structural principle diagram of the three-level PID control loop provided by the present invention. DETAILED DESCRIPTION

[0041] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0042] The embodiment of the present invention discloses a high-precision and high-efficiency control method for a biomass gas-charcoal cogeneration system. The control method is applied in the biomass gas-charcoal cogeneration system to solve the problem of uncoordinated individual control of parameters such as temperature, pressure, blower flow, gas flow, gas quality, and gas pressure in the biomass gas-charcoal cogeneration system. The control method uses a multivariable coupling control strategy, which mainly solves the problem that the temperature in the furnace cannot be zoned when a single control is used, the gas production quality and the gasification furnace cannot be coupled and controlled, resulting in a large amount of tar in the gas, making the quality of the combustible gas difficult to control and the gasification furnace low in efficiency. The method aims to accurately control the gasification effect, reduce the tar content in the gas, and achieve gas-charcoal cogeneration to improve the efficiency of the gasification furnace.

[0043] The structure of the biomass gas-charcoal cogeneration system is as follows: Figure 1 As shown, it specifically includes: a first loader M01, a second loader M02, a buffer silo, a tower grate M03, a gasifier blower M4 and a gas induced draft fan M5; a plurality of temperature transmitters T01, T02, T03, T04 and T05 are installed from top to bottom in the gasifier; a level meter L01 is installed on the top of the gasifier; an upper level meter L2 and a lower level meter L3 are installed in the buffer silo respectively; the gasifier blower M4 is connected to the gasifier through a pipeline, and an electric control valve and a blast flow meter F01 are installed on the pipeline; the lower layer of the gasifier is installed There is a pressure transmitter P01; a temperature transmitter T07 is installed on the tower grate M03; the gas layer of the gasifier is connected to the input end of the gas draft fan M5 through a gas pipeline, and the output end of the gas draft fan M5 is connected to the gas-consuming equipment through a gas pipeline, an electric control valve and a temperature transmitter T08 are installed on the gas pipeline between the gas layer of the gasifier and the input end of the gas draft fan M5, and a gas flow meter F02, a gas pressure transmitter P03 and an oxygen analyzer Al1 are installed on the gas pipeline between the output end of the gas draft fan M5 and the gas-consuming equipment.

[0044] The gasifier is divided into a gas layer, a drying layer, a pyrolysis layer, a reduction layer and an oxidation layer from top to bottom;

[0045] The core area temperature of the drying layer is 100-150℃, the material is dehydrated and dried, most of the water is precipitated below 105℃, and then the temperature rises rapidly.

[0046] The core zone temperature of the pyrolysis layer is 300-700℃, and the high molecular organic matter begins an endothermic irreversible thermal decomposition reaction. The higher the temperature, the more intense the reaction. The products are a complex mixed gas and solid carbon. The mixed gas includes at least hundreds of hydrocarbons, some of which can be condensed into tar at room temperature.

[0047] The reduction layer mainly undergoes endothermic reactions, with the core temperature at 700-900°C. The chemical reaction formula is: C+CO2=2CO, C+H2O(g)=CO+H 2 ,C+H2O(g)=CO2+2H 2 ,C+2H 2 =CH4, CO+H2O(g)=CO2+H2.

[0048] The oxide layer undergoes an exothermic reaction, with the core temperature at 1000-1350°C. The chemical reaction formula is: CO+O2=CO 2， 2CO+O2=CO2.

[0049] The temperature transmitter T01 feeds back the temperature of the oxidation layer, the temperature transmitter T02 feeds back the temperature of the reduction layer, the temperature transmitter T03 feeds back the temperature of the pyrolysis layer, the temperature transmitter T04 feeds back the temperature of the drying layer, the temperature transmitter T05 feeds back the temperature of the gas layer, the temperature transmitter T07 feeds back the temperature of the carbon ash layer, and the temperature transmitter T08 feeds back the temperature of the gas pipeline.

[0050] The gasifier blower M4 is a variable frequency blower, which is used to provide sufficient O2 for the reaction in the gasifier. The blower flowmeter F01 feeds back the flow rate of O2, and the biomass furnace lower layer pressure transmitter P01 feeds back the blower's blower pressure.

[0051] The upper level meter L2 and the lower level meter L3 feedback the material level of the buffer silo.

[0052] The first loader M01 adopts a lifting loader, which is used to lift the materials in the silo into the buffer silo, and the second loader M02 adopts an auger feeder, which is used to drive the materials in the buffer silo to feed into the gasifier.

[0053] The induced draft fan M5 of the gasifier extracts the gas, the gas flow meter F02 feeds back the flow rate of the gas, the oxygen analyzer AI1 feeds back the oxygen content in the gas, and the pressure transmitter P03 feeds back the pressure of the gas pipeline.

[0054] The tower grate M03 discharges the carbon slag after the oxide layer is burned out of the furnace body.

[0055] The present invention uses three-level PID control to control the upper and lower layer temperatures and gas production quality in the furnace. The specific method is as follows:

[0056] How to build a biomass gas-char cogeneration system Figure 2The three-level PID control loop shown includes an upper control loop, a lower control loop and a gas control loop;

[0057] Adaptively adjust the feed rate of the gasifier based on the upper control loop;

[0058] Adaptively adjust the air volume of the gasifier blower based on the lower control loop;

[0059] The induced air volume of the induced draft fan of the gasifier is adaptively adjusted based on the fuel gas control loop.

[0060] The three control loops mentioned above are described in detail below.

[0061] 1) The upper control loop includes an upper main regulator and an upper sub-regulator;

[0062] The upper main regulator performs PID calculation according to the target value of the upper control temperature of the gasifier (i.e., the upper main set value) and the actual temperature value collected by the upper temperature sensor in the gasifier (i.e., the upper main measured value), and obtains the result a;

[0063] The upper sub-regulator performs the following calculation based on the result a, the feedback value b of the oxygen content in the gasifier, and the coefficients k1 and k2: k1*a-K2*b, and converts the calculation result into the height control value of the material. The action of the feed motor is controlled according to the height control value. At the same time, the material height in the gasifier (i.e., the upper sub-measurement value) is fed back to the upper sub-regulator in real time. At different temperature values, the calculation result a has different values ​​in the CPU, and the feedback value b of the oxygen content also corresponds to different digital quantities. The calculation results of k1*a-K2*b correspond to different height control values. In the actual operation process, the corresponding height control value is directly retrieved from the pre-stored corresponding relationship according to the calculation result.

[0064] If the actual temperature value collected by the upper temperature transmitter in the gasifier is less than the target value of the upper control temperature, the result a of the upper main regulator operation decreases, and the height control value also decreases accordingly. At this time, the upper sub-regulator controls the feed motor to reduce the feed speed;

[0065] If the actual temperature value collected by the upper temperature transmitter in the gasifier is greater than the target value of the upper control temperature, the calculation result a of the upper main regulator increases, and the height control value also increases accordingly. At this time, the upper sub-regulator controls the feed motor to increase the feed speed;

[0066] If the feedback value b of the oxygen content in the gasifier increases, the upper sub-regulator controls the feed motor to reduce the feed speed.

[0067] The main control loop of the upper control loop is used to control the temperature in the upper gasifier (i.e. the upper main control variable), and the sub-control loop is used to control the height of the material layer in the gasifier (i.e. the upper sub-control variable). The feedback value b of the oxygen content in the gasifier is fed back to the upper sub-regulator, and the oxygen in the lower layer of the micro-positive pressure gasifier in the gasifier blower control room has been consumed at the bottom layer. The auger feed will bring in oxygen, and some of the oxygen from the upper layer will be sucked out by the induced draft fan without reacting after it comes in. At this point, the oxygen content is fed back to balance the material consumption, feed rate, temperature value and oxygen content.

[0068] The PID of the sub-regulator of the upper control loop adjusts the speed of the feed motor to adjust the sub-control variable of the material level height in the furnace body. The output value of the main regulator PID of the upper control loop is used as the given value of the sub-regulator PID to correct the speed of the gasifier feed motor to adjust the main control variable of the upper temperature in the furnace body. The material height in the gasifier is fed back to the upper sub-regulator in real time. By controlling the action of the feed motor, the material height in the furnace body is controlled between 8.7-10.7 meters. At the same time, the upper temperature in the furnace body is controlled between 95℃-145℃, because the height of the material can block the heat generated by the combustion of the oxidation layer, the heat absorbed by the reduction layer reaction, the heat absorbed by the pyrolysis layer, and the heat absorbed by the drying layer. The higher the height of the material, the lower the temperature of the gas layer. While ensuring the optimal reaction temperature of the gasifier, the material height and the feed speed are adjusted in real time. The upper main regulator sets the output result of the upper temperature area to be controlled as the input of the sub-regulation, and the output result of the sub-regulator controls the feeding of the feed motor.

[0069] 2) The lower control loop includes a lower main regulator and a lower sub-regulator;

[0070] The lower layer main regulator performs PID calculation according to the target value of the lower layer control temperature of the gasifier (i.e., the lower layer main set value) and the actual temperature value collected by the lower layer temperature sensor in the gasifier (i.e., the lower layer main measured value), and obtains the result A;

[0071] The lower-layer sub-regulator performs the following calculation based on the result A, the lower-layer pressure value B in the gasifier, and the coefficients K3 and K4: K3*A-k4*B, and converts the calculation result into the air volume control value. The action of the gasifier blower is controlled according to the air volume control value. At the same time, the air volume of the gasifier blower (i.e., the lower-layer sub-measurement value) is fed back to the lower-layer sub-regulator in real time. At different temperature values, the calculation result A has different values ​​in the CPU, and the lower-layer pressure value B in the gasifier also corresponds to different digital quantities. The calculation results of K3*A-k4*B correspond to different air volume control values. In the actual operation process, the corresponding air volume control value is directly retrieved from the pre-stored corresponding relationship according to the calculation result.

[0072] If the actual temperature value collected by the lower temperature sensor in the gasifier is less than the target value of the lower control temperature, the result A of the lower main regulator operation increases, and the air volume control value also increases accordingly. At this time, the lower sub-regulator controls the gasifier blower to increase the air volume;

[0073] If the actual temperature value collected by the lower temperature sensor in the gasifier is greater than the target value of the lower control temperature, the result A of the lower main regulator operation decreases, and the air volume control value also decreases accordingly. At this time, the lower sub-regulator controls the gasifier blower to reduce the air volume.

[0074] The pressure value B is used as a forward feedback to adjust the fan speed to prevent the air volume from increasing or decreasing too quickly. The air volume of the gasifier blower directly affects the pressure. The larger the air volume, the greater the pressure, and the smaller the air volume, the lower the pressure, which is a linear trend.

[0075] The height of the material in the furnace can be calculated by the following formula:

[0076] 3.14*R 2 (Radius of gasifier)*H(Height of radar level meter)*Qm(Mass of material)=Material weight.

[0077] The material consumption D can be calculated by the formula AFR (the amount of air entering the furnace) = V0 (theoretical amount of air for complete combustion of the designed raw materials) * FCR (amount of fuel consumed) * ε (air equivalence ratio), where the amount of air entering the furnace AFR (obtained by the blower air volume meter (F01)) is known, and the material consumption D can be calculated by the formula:

[0078] D = AFR (amount of air entering the furnace) / (V0 (theoretical amount of air for complete combustion of designed raw materials) * ε (air equivalence ratio)). It can be seen that the air volume of the gasifier blower not only controls the temperature of the lower physical and chemical reaction, but also controls the amount of O2 in the gasifier and the consumption of raw materials, ensuring a slight positive pressure in the lower layer of the furnace body. The purpose of ensuring the pressure in the lower layer of the gasifier is to allow the oxygen in the air to react completely and prevent the bottom oxygen from entering the furnace body, thereby reducing the oxygen content in the combustible gas, improving the gas quality, and reducing the risk of combustion and explosion.

[0079] The main control loop of the lower control loop is used to control the temperature in the lower gasifier (i.e., the lower main control variable), and the sub-control loop is used to control the air volume of the blower in the gasifier (i.e., the lower sub-controlled variable). The sub-regulator (PID) of the lower control loop converts and compares the calculation value of the main regulator (PID) and the feedback value of the lower micro-positive pressure and air volume of the gasifier to adjust the air volume of the gasifier blower to control the lower temperature and lower micro-positive pressure of the gasifier.

[0080] The air volume of the gasifier blower is fed back to the lower sub-regulator in real time. By controlling the action of the gasifier blower, the micro-positive pressure in the furnace is controlled at 1KPA, and the air volume of the gasifier blower is maintained at 1100m 3 / h-5700m 3 / h, the temperature of the lower layer in the gasifier is controlled at 920℃-1370℃, because the oxidation reaction (CO+O2=CO 2， 2CO+O2=CO2) mainly reacts with O2 in the air. The greater the air volume blown in by the blower, the more intense the reaction, and the higher the heat generated (due to the nature of biomass materials, the maximum temperature is below 1400 degrees Celsius). While ensuring the optimal reaction temperature of the gasifier, the air volume and air pressure of the gasifier blower are adjusted in real time for coordinated regulation. The lower main regulator sets the output result of the temperature zone to be controlled in the lower layer as the input of the sub-regulator. The output result of the lower sub-regulator controls the air volume of the blower, and the temperature of the oxidation reaction is controlled by the size of the air volume.

[0081] 3) The gas control loop includes a gas main regulator and a gas sub-regulator;

[0082] The amount of gas produced E (E = K*D, k is the empirical coefficient 2-3m 3 / Kg), the air volume of the induced draft fan of the gasifier controls the negative pressure in the upper layer of the gasifier, and also controls the pressure of the gas pipeline and the flow rate of the gas.

[0083] The gas main regulator calculates the gas volume input value Z of the gas-using equipment, the actual temperature value T1 collected by the lower temperature sensor in the gasifier, and the coefficients K5 and K6 as follows: K5*Z+k6*T1, and converts the calculation result into the gas flow value A1; taking the 13-bit CPU as an example, K5 and K6 are coefficient values, which are set according to the importance of the data, K5=70%, K6=30%. Convert the engineering quantity of the Z value and the engineering quantity of the temperature value T1 into digital quantities and then calculate them uniformly.

[0084] The gas sub-regulator calculates K7*A1-k8*B1 based on the gas flow value A1, the upper pressure value B1 of the gasifier, and the coefficients K7 and K8, and converts the calculation result into a pressure control value, and controls the action of the gasifier induced draft fan according to the pressure control value. When the gas volume input value Z of the gas-using equipment or the actual temperature value T1 collected by the lower temperature sensor in the gasifier increases, the calculation result of K7*A1-k8*B1 will also increase, and at this time, the induced air volume of the gasifier induced draft fan needs to be increased.

[0085] The measured value of the gas flow meter (i.e. the main controlled variable) is fed back to the main gas regulator in real time, and the pressure in the gas pipeline (i.e. the secondary controlled variable) is fed back to the secondary gas regulator in real time. The main control loop of the gas control loop controls the gas flow, the secondary control loop controls the flue gas pressure, the main control loop feedforwards the lower temperature in the furnace, and the secondary control loop feedforwards the upper negative pressure in the furnace body. The secondary control loop feedforwards the negative pressure in the upper layer of the furnace body. The secondary regulator (PID) of the gas control loop adjusts the gasifier induced draft fan to control the flow and pressure of the gas by converting and comparing the calculated value of the main regulator (PID) and the negative pressure in the upper layer of the furnace body and the feedback value of the gas pipeline. The main regulator (PID) of the gas control loop converts and compares the input value of the gas volume of the gas-using equipment and the temperature value of the layer in the gasifier (the higher the temperature of the gasifier, the greater the gas production). By controlling the action of the gasifier induced draft fan, the pressure of the gas pipeline is maintained between 9kpa-20kpa, and the gas flow is maintained at 4000m 3 / h-8000m 3 / h.

[0086] In addition, the present invention installs a temperature transmitter T07 at the grate position of the gasifier, and the temperature transmitter T07 is used to detect the temperature of the ash in the furnace body; by setting the ash discharge temperature, the switching of the gasification furnace gas production and carbon production working modes is realized. When a large amount of gas is required, the ash discharge temperature is set to 710°C, the slag discharge speed of the grate is slowed down, and the carbon and oxygen elements in the raw materials are allowed to react as much as possible to increase the gas production; when the gas demand decreases, the ash discharge temperature is set to 912°C, the slag discharge speed of the grate is accelerated, and the reaction time of the carbon and oxygen elements in the raw materials is reduced, and the ash with a higher carbon content is discharged for carbon production, thereby reducing gas and improving the efficiency of the gasifier.

[0087] In general, the core idea of ​​the present invention using three double-cascade PID control methods is to use errors to eliminate errors. The difference between the target value and the actual value is obtained through PID control to obtain the input quantity, and the actual value is continuously corrected to make it closer to the target value. The advantages of three-cascade hierarchical control are fast response, small overshoot, small static error, less oscillation and low cost.

[0088] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0089] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A high-precision and high-efficiency control method for a biomass gas-char cogeneration system, characterized in that: include: Constructing a three-level PID control loop for a biomass gas-char cogeneration system, wherein the three-level PID control loop includes an upper control loop, a lower control loop and a gas control loop; Adaptively adjusting the feed amount of the gasifier based on the upper control loop; Adaptively adjusting the air volume of the gasifier blower based on the lower control loop; The induced air volume of the induced draft fan of the gasifier is adaptively adjusted based on the fuel gas control loop.

2. The control method of the high-precision and high-efficiency biomass gas-char cogeneration system according to claim 1 is characterized in that: The biomass gas-char cogeneration system comprises: a first loader, a second loader, a buffer silo, a tower grate, a gasifier blower and a gas induced draft fan; a plurality of temperature transmitters are installed from top to bottom inside the gasifier; level meters are installed in the buffer silo and on the top of the gasifier; The first loader is used to lift the material in the silo into the buffer silo; The second loader is used to drive the material in the buffer silo into the gasifier; The gasifier blower is used to provide oxygen for the reaction in the gasifier, and a blower flow meter is installed on the pipeline between the gasifier blower and the gasifier; The gas induced draft fan is used to extract the gas in the gasifier; a temperature transmitter is installed on the gas pipeline between the input end of the gas induced draft fan and the gasifier; a gas flow meter, a gas pressure transmitter and an oxygen analyzer are installed on the gas pipeline between the output end of the gas induced draft fan and the gas-using equipment.

3. The control method of the high-precision and high-efficiency biomass gas-char cogeneration system according to claim 1 is characterized in that: The upper control loop includes an upper main regulator and an upper sub regulator; The upper main regulator performs PID calculation according to the target value of the upper control temperature of the gasifier and the actual temperature value collected by the upper temperature sensor in the gasifier to obtain the result a; The upper sub-regulator performs the following calculation based on the result a, the feedback value b of the oxygen content in the gasifier, and the coefficients k1 and k2: k1*a-K2*b, converts the calculation result into a height control value of the material, and controls the action of the feed motor based on the height control value; If the actual temperature value collected by the upper temperature transmitter in the gasifier is less than the target value of the upper control temperature, the result a of the upper main regulator operation decreases, and the height control value also decreases accordingly. At this time, the upper auxiliary regulator controls the feed motor to reduce the feed speed; If the actual temperature value collected by the upper temperature transmitter in the gasifier is greater than the target value of the upper control temperature, the calculation result a of the upper main regulator increases, and the height control value also increases accordingly. At this time, the upper auxiliary regulator controls the feed motor to increase the feed speed; If the feedback value b of the oxygen content in the gasifier increases, the upper sub-regulator controls the feed motor to reduce the feed speed.

4. The control method of the high-precision and high-efficiency biomass gas-char cogeneration system according to claim 3 is characterized in that: The material height in the gasifier is fed back to the upper sub-regulator in real time, and the material height in the gasifier is maintained between 8.7 meters and 10.7 meters by controlling the action of the feed motor. Within this material height range, the upper temperature of the gasifier is maintained between 95°C and 145°C.

5. The control method of the high-precision and high-efficiency biomass gas-char cogeneration system according to claim 1 is characterized in that: The lower control loop includes a lower main regulator and a lower sub regulator; The lower layer main regulator performs PID calculation according to the target value of the lower layer control temperature of the gasifier and the actual temperature value collected by the lower layer temperature sensor in the gasifier to obtain the result A; The lower layer sub-regulator performs the following calculation based on the result A, the lower layer pressure value B in the gasifier and the coefficients K3 and K4: K3*A-k4*B, converts the calculation result into an air volume control value, and controls the action of the gasifier blower based on the air volume control value; If the actual temperature value collected by the lower temperature sensor in the gasifier is less than the target value of the lower control temperature, the result A of the lower main regulator operation increases, and the air volume control value also increases accordingly. At this time, the lower auxiliary regulator controls the gasifier blower to increase the air volume; If the actual temperature value collected by the lower temperature sensor in the gasifier is greater than the target value of the lower control temperature, the result A of the lower main regulator operation decreases, and the air volume control value also decreases accordingly. At this time, the lower sub-regulator controls the gasifier blower to reduce the air volume.

6. The control method of the high-precision and high-efficiency biomass gas-char cogeneration system according to claim 5 is characterized in that: The air volume of the gasifier blower is fed back to the lower sub-regulator in real time, and the air volume of the gasifier blower is maintained at 1100m 3 / h-5700m 3 / h range, within this air supply volume range, the temperature of the lower layer of the gasifier is maintained between 920℃-1370℃.

7. The control method of the high-precision and high-efficiency biomass gas-char cogeneration system according to claim 5 is characterized in that: The air volume of the gasifier blower controls the material consumption, and its expression is: Material consumption D = amount of air entering the furnace AFR / (theoretical amount of air for complete combustion of designed raw materials V0*air equivalent ratio ε).

8. The control method of the high-precision and high-efficiency biomass gas-char cogeneration system according to claim 1 is characterized in that: The gas control ring includes a gas main regulator and a gas sub-regulator; The gas main regulator calculates the following value based on the gas volume input value Z of the gas-using equipment, the actual temperature value T1 collected by the lower temperature sensor in the gasifier, and the coefficients K5 and K6: K5*Z+k6*T1, and converts the calculation result into the gas flow value A1; The gas auxiliary regulator calculates K7*A1-k8*B1 according to the gas flow value A1, the gasifier upper layer pressure value B1 and the coefficients K7 and K8, converts the calculation result into a pressure control value, and controls the action of the gasifier induced draft fan according to the pressure control value.

9. The control method of the high-precision and high-efficiency biomass gas-char cogeneration system according to claim 8, characterized in that: The pressure in the gas pipeline is fed back to the gas auxiliary regulator in real time. By controlling the operation of the gasifier induced draft fan, the pressure of the gas pipeline is maintained between 9kpa-20kpa and the gas flow rate is maintained at 4000m 3 / h-8000m 3 / h.

10. The control method of the high-precision and high-efficiency biomass gas-char cogeneration system according to claim 1, characterized in that: A temperature transmitter is installed at the grate position of the gasifier, which is used to detect the temperature of the ash in the furnace body; by setting the ash discharge temperature, the switching of the gasification furnace's gas production and carbon production working modes is achieved. When a large amount of gas is required, the ash discharge temperature is set to 710°C to slow down the slag discharge speed of the grate; when the gas demand decreases, the ash discharge temperature is set to 912°C to speed up the slag discharge speed of the grate.

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