阅读说明：本技术 一种湿法脱硫罗茨风机节能控制系统及方法 (Energy-saving control system and method for wet desulphurization Roots blower ) 是由 谭琨 卞友斌 周自阳 张方醒 王晓东 于 2021-09-30 设计创作，主要内容包括：本发明提供本发明公开了一种湿法脱硫罗茨风机节能控制系统及方法,根据湿法脱硫装置脱除的SO-(2)总量或脱硫装置入口烟气量、入口烟气中的SO-(2)浓度、出口烟气量、出口烟气中的SO-(2)排放浓度值自动计算理论需氧量；通过氧化风管道流速、石膏品质双重限制条件,自动调节氧化风机电机频率,达到最佳的节能效果。本发明采用了一种湿法脱硫罗茨风机节能控制方法,自动化程度高,克服了传统脱硫浆液氧化控制方法的脱硫浆液亚硫酸盐需氧量与实际氧化风机风量之间的不匹配、过氧化现象频繁出现的情况,在保证石膏质量和脱硫装置安全稳定运行的同时实现氧化风机节能。(The invention provides an energy-saving control system and method for a Roots blower for wet desulphurization, which is used for controlling SO removed by a wet desulphurization device 2 Total amount or amount of flue gas at inlet of desulfurization apparatus, SO in inlet flue gas 2 Concentration, outlet flue gasMeasuring SO in outlet flue gas 2 Automatically calculating theoretical oxygen demand of the emission concentration value; the motor frequency of the oxidation fan is automatically adjusted through dual limiting conditions of the flow speed of the oxidation air pipeline and the quality of gypsum, and the optimal energy-saving effect is achieved. The energy-saving control method for the wet desulphurization Roots blower is high in automation degree, overcomes the defects of mismatching between the sulfite oxygen demand of the desulphurization slurry and the actual air quantity of the oxidation blower and frequent occurrence of peroxidation in the traditional desulphurization slurry oxidation control method, and realizes energy saving of the oxidation blower while ensuring the quality of gypsum and safe and stable operation of a desulphurization device.)

1. The energy-saving control system for the wet desulphurization Roots blower comprises an absorption tower and is characterized in that a Roots blower (1), a desulphurization inlet CEMS (2), a DCS control system (3), an induced draft fan (4), an edge intelligent control integrated machine (5), an oxidation blower variable-frequency control cabinet (6) and a desulphurization outlet CEMS (7) are arranged in the system; an absorption tower discharge pump (8), a gypsum cyclone (9), a vacuum belt conveyor (10) and a gypsum warehouse (11);

the Roots blower (1) is connected with the absorption tower; the desulfurization inlet CEMS (2) is arranged on an inlet pipeline of the absorption tower and is respectively connected with the DCS control system (3) and the induced draft fan (4); the desulfurization outlet CEMS (7) is arranged at a delay outlet book of the absorption tower and is connected with the DCS control system (3); the DCS control system (3) is connected with the oxidation fan variable-frequency control cabinet (6); the oxidation fan variable-frequency control cabinet (4) is connected with the Roots fan (1); the edge intelligent control integrated machine (5) is connected with the DCS control system (3); an oxidized wind algorithm model (51) is embedded in the edge intelligent control all-in-one machine; collecting operation parameters through a desulfurization inlet CEMS (2), and uploading the collected data to a DCS (distributed control system) (3); the absorption tower discharge pump (8) is arranged at the bottom of the absorption tower and is connected with the absorption tower through a pipeline; the absorption tower discharge pump (8) is also connected to a gypsum cyclone (9) arranged outside the absorption tower through a pipeline; and conveying the dehydrated gypsum to the gypsum warehouse (11) through the vacuum belt conveyor (10).

2. A wet desulphurization Roots blower energy-saving control system method is characterized in that: the method comprises the following steps:

s1-1: installing a measuring device on the flue in front of the absorption tower and behind the induced draft fan, and detecting and obtainingSO entering a desulfurizing tower₂Data of concentration, flue gas flow, installation temperature measurement, humidity, oxygen content and pressure;

s1-2: a measuring device is arranged at an outlet at the upper end of the absorption tower to detect and obtain SO discharged from an outlet of the desulfurization tower₂Data of concentration, flue gas flow, temperature, humidity, oxygen content and pressure;

the data measured by the measuring device are respectively uploaded to an entrance CEMS through network signals; then the data is transmitted to a DCS control system through a network signal;

s2: the edge intelligent control all-in-one machine acquires the data acquired in the step S1 from the DCS control system, and the oxidation wind algorithm model in the edge intelligent control all-in-one machine is calculated to obtain the air quantity required by the desulfurization and oxidation system; by collecting the flue gas amount Q1 and SO of the desulfurization inlet in the DCS control system₂Concentration C1, desulfurization outlet flue gas amount Q2 and desulfurization outlet SO₂Concentration C2; the collected data are converted numerical values, and the states of the collected data are standard conditions, dry basis and reference oxygen;

s3: performing further calculation through the air amount calculated in the step S2 to obtain the minimum operation frequency required by the operation condition of the on-site desulfurization system;

according to the diameter phi of the pipeline of the oxidation fan, the lowest allowable flow rate is a; obtaining the lowest air volume V2 passing through the oxidation air pipeline; further obtaining a required air volume V20 corresponding to the generated air volume V2;

s4: the result calculated in the edge intelligent control integrated machine is fed back to the desulfurization DCS system through network signals, and then the signals are transmitted to the oxidation fan frequency converter through the DCS control system and are converted into voltage and current signals to the oxidation fan to realize the adjustment of the oxidation air quantity;

s5: after the edge intelligent control all-in-one machine operates for a period of time, detecting the quality of gypsum; according to the detection result of the quality of the gypsum, the oxidation rate n in the step S2 is adjusted, and then the oxidation rate n is cured, so that the content of the calcium sulfite hemihydrate in the gypsum is ensured to be less than or equal to 0.50%.

3. The energy-saving control method for the wet desulphurization Roots blower as claimed in claim 2, characterized in that: the method also comprises an operation control protection method; the protection method automatically controls and adjusts the operation of the wet desulphurization oxidation system through modes of PID regulation, filtering, fitting, adaptive learning and the like; when the operation program of the edge intelligent control all-in-one machine is abnormal, the operation program is automatically switched to the original DCS control program, and the safe and stable operation of the desulfurization system is ensured.

4. The energy-saving control method for the wet desulphurization Roots blower as claimed in claim 2, characterized in that: detected SO₂The concentration, the flue gas flow, the temperature, the humidity, the oxygen content and the pressure are all online continuous measurement values.

5. The energy-saving control method for the wet desulphurization Roots blower as claimed in claim 2, characterized in that: the Roots blower (1) is arranged in a one-use one-standby mode; and the oxidation fan variable-frequency control cabinet (6) gives a signal to the Roots fan (1).

6. The energy-saving control method for the wet desulphurization Roots blower as claimed in claim 2, characterized in that: two operation modes are set in the DCS control system; the mode comprises an edge intelligent control all-in-one machine mode and a DCS control mode.

Technical Field

The invention relates to the field of wet desulphurization environmental protection island control, in particular to a wet desulphurization Roots blower energy-saving control system and method.

Background

Limestone-gypsum wet desulphurization is the most widely applied flue gas desulphurization technology at the present stage, and is mainly used for sulfur dioxide in flue gas. The technical principle is that SO in the flue gas₂And the gypsum is generated by chemical reaction with limestone slurry through oxidation and crystallization. In the desulfurization process, a large amount of oxidizing air needs to be blown in the reaction of oxidizing the calcium sulfite into the calcium sulfate. The conventional desulfurization system adopts a mode of blowing excessive air to promote the reaction of calcium sulfite and oxygen.

At present, a desulfurization system is put into operation, and an oxidation fan adopts a continuous operation mode. Some energy-conserving transformation has been carried out to oxidation system to some power plants, iron and steel plant, coke-oven plant, changes oxidation fan motor into inverter motor, permanent magnetism inverter motor, also plays some energy-conserving effects really, but the effect is not very obvious to often need the manual work to adjust, the oxidation degree of the desulfurization thick liquid of unable accurate control, consequently often have the phenomenon of overoxidation or under-oxidation to take place, bring the potential safety hazard for desulfurization system safety and stability operation.

Disclosure of Invention

The invention aims to solve the defects in the prior art, and provides a wet desulphurization Roots blower energy-saving control system and method.

In order to achieve the purpose, the invention adopts the following technical scheme: a wet desulphurization Roots blower energy-saving control system comprises an absorption tower, wherein a Roots blower, a desulphurization inlet CEMS, a DCS control system, an induced draft fan, an edge intelligent control integrated machine, an oxidation blower variable frequency control cabinet and a desulphurization outlet CEMS are arranged in the system; the system comprises an absorption tower discharge pump, a gypsum cyclone, a vacuum belt conveyor and a gypsum warehouse; the Roots blower is connected with the absorption tower; the desulfurization inlet CEMS is arranged on an inlet pipeline of the absorption tower and is respectively connected with the DCS control system and the induced draft fan; the desulfurization outlet CEMS is arranged at a delay outlet book of the absorption tower and is connected with the DCS control system; the DCS control system is connected with the oxidation fan variable frequency control cabinet; the oxidation fan variable-frequency control cabinet is connected with the Roots fan; the edge intelligent control all-in-one machine is connected with the DCS control system; an oxidizing wind algorithm model is embedded in the edge intelligent control all-in-one machine; collecting operation parameters through a desulfurization inlet CEMS, and uploading the collected data to a DCS (distributed control System); the absorption tower discharge pump is arranged at the bottom of the absorption tower and is connected with the absorption tower through a pipeline; the absorption tower discharge pump is also connected to a gypsum cyclone arranged outside the absorption tower through a pipeline; and conveying the dehydrated gypsum to the gypsum warehouse through the vacuum belt conveyor.

A wet desulphurization Roots blower energy-saving control system method comprises the following steps:

s1-1: installing a measuring device on a flue behind an induced draft fan in front of an absorption tower, and detecting and obtaining data of SO2 concentration, flue gas flow, installation temperature measurement, humidity, oxygen content and pressure entering a desulfurizing tower;

s1-2: installing a measuring device at an outlet at the upper end of the absorption tower, and detecting and obtaining data of SO2 concentration, flue gas flow, temperature, humidity, oxygen content and pressure discharged from an outlet of the desulfurization tower;

the data measured by the measuring device are respectively uploaded to an entrance CEMS through network signals; then the data is transmitted to a DCS control system through a network signal;

s2: the edge intelligent control all-in-one machine acquires the data acquired in the step S1 from the DCS control system, and the oxidation wind algorithm model in the edge intelligent control all-in-one machine is calculated to obtain the air quantity required by the desulfurization and oxidation system; collecting the desulfurization inlet flue gas volume Q1, the desulfurization inlet SO2 concentration C1, the desulfurization outlet flue gas volume Q2 and the desulfurization outlet SO2 concentration C2 in a DCS control system; the collected data are converted numerical values, and the states of the collected data are standard conditions, dry basis and reference oxygen;

removing W1 (Q1 × C1-Q2 × C2)/106 by weight of SO 2;

the required oxygen amount O1 is n multiplied by W1/64 multiplied by 16, n is the oxidation rate, and is 2.5-3.5;

the preliminary value of n is related to the concentration C1 of SO 2;

when C1 is less than or equal to 2500mg/Nm³N takes the value of 2.5;

when the carbon content is more than 2500 and less than or equal to 5000mg/Nm and 1³N takes the value of 3.0;

when C1 is greater than 5000mg/Nm³N takes the value of 3.5;

the required air amount V1 is L1 × O1, and L1 is a coefficient;

s3: performing further calculation through the air amount calculated in the step S2 to obtain the minimum operation frequency required by the operation condition of the on-site desulfurization system;

according to the diameter phi of the pipeline of the oxidation fan, the lowest allowable flow rate is a; obtaining the lowest air volume V2 passing through the oxidation air pipeline; further obtaining a required air volume V20 corresponding to the generated air volume V2;

V2＝3.14×(φ/2)2×a；

v20 ═ V2 × k, k being a coefficient;

the lowest allowable frequency is f1 ═ V20/V0 × 50;

the air volume V0 of the original oxidation fan is 50 Hz. The theoretical calculation running frequency is f-V1/V0 x 50,

when the theoretically calculated running frequency f is lower than the lowest allowable frequency f1, the lowest running frequency is f 1;

when the theoretically calculated running frequency f is higher than the lowest allowable frequency f1, taking f as the lowest running frequency;

s4: the result calculated in the edge intelligent control integrated machine is fed back to the DCS control system through network signals, and then the signals are transmitted to the frequency converter of the oxidation fan through the DCS control system and are converted into voltage and current signals to be sent to the oxidation fan to realize the adjustment of the oxidation air quantity;

s5: after the edge intelligent control all-in-one machine operates for a period of time, detecting the quality of gypsum; according to the detection result of the gypsum quality, adjusting the oxidation rate n in the step S2, and then curing the oxidation rate n to ensure that the content of calcium sulfite hemihydrate in the gypsum is less than or equal to 0.50%;

the content of calcium sulfite hemihydrate (CaSO3 & 1/2H2O) in the qualified gypsum is less than or equal to 0.50 percent; the quality of the gypsum is mainly determined by the oxidation effect of calcium sulfite hemihydrate (CaSO3 & 1/2H 2O); the better the oxidation effect, the lower the content of calcium sulfite hemihydrate (CaSO3 & 1/2H2O) in the gypsum; the oxidation effect is closely related to the amount of oxidation air blown into the desulfurization tower by the oxidation fan.

Preferably, the method further comprises an operation control protection method; the protection method automatically controls and adjusts the operation of the wet desulphurization oxidation system through modes of PID regulation, filtering, fitting, adaptive learning and the like; when the operation program of the edge intelligent control all-in-one machine is abnormal, the operation program is automatically switched to the original DCS control program, and the safe and stable operation of the desulfurization system is ensured.

Preferably, the detected SO2 concentration, flue gas flow, temperature, humidity, oxygen content and pressure are all online continuous measurement values.

Preferably, the Roots blower is arranged in a one-use-one-standby mode; and the oxidation fan variable-frequency control cabinet gives a signal to the Roots fan.

Preferably, two operation modes are set in the DCS control system; the mode comprises an edge intelligent control all-in-one machine mode and a DCS control mode.

Compared with the prior art, the invention has the beneficial effects that:

(1) energy conservation and consumption reduction, the frequency of the oxidation fan is adjusted according to the actual operation condition, and the oxidation air quantity is adjusted.

(2) The oxidation effect is ensured, the quality of the gypsum can be ensured by taking the content of the calcium sulfite hemihydrate (CaSO3 & 1/2H2O) in the desulfurized gypsum as a working basis, and the system operation is safer and more stable.

(3) And intelligent control, namely, data are detected through an inlet and an outlet CEMS, and a data signal obtained through calculation is directly acted on the frequency converter of the oxidation fan through algorithm calculation, so that manual operation is reduced.

Drawings

FIG. 1 is a flow chart of an energy-saving control system of a wet desulphurization Roots blower;

FIG. 2 is a flow chart of an energy-saving control method of a wet desulphurization Roots blower;

in the figure: 1-Roots blower; 2-desulfurization inlet CEMS; 3-DCS control system; 4-a draught fan; 5, intelligently controlling an integrated machine at the edge; 6-oxidizing the variable frequency control cabinet of the fan; 7-desulfurization outlet CEMS; 8-discharging from the absorption tower; 9-a gypsum cyclone; 10-vacuum belt conveyor; 11-a gypsum warehouse; 51-oxidation wind algorithm model.

Detailed Description

In order to further understand the objects, structures, features and functions of the present invention, the following embodiments are described in detail.

Referring to fig. 1 and fig. 2 in combination, the invention provides an energy-saving control system and method for a wet desulphurization roots blower, comprising an absorption tower, wherein a roots blower 1, a desulphurization inlet CEMS 2, a DCS control system 3, an induced draft fan 4, an edge intelligent control integrated machine 5, an oxidation blower variable frequency control cabinet 6 and a desulphurization outlet CEMS 7 are arranged in the system; an absorption tower discharge pump 8, a gypsum cyclone 9, a vacuum belt conveyor 10 and a gypsum warehouse 11; the Roots blower 1 is connected with the absorption tower; the desulfurization inlet CEMS 2 is arranged on an inlet pipeline of the absorption tower and is respectively connected with the DCS control system 3 and the induced draft fan 4; the desulfurization outlet CEMS 7 is arranged at a delay outlet book of the absorption tower and is connected with the DCS control system 3; the DCS control system 3 is connected with the oxidation fan variable frequency control cabinet 6; the oxidation fan variable-frequency control cabinet 6 is connected with the Roots fan 1; the edge intelligent control integrated machine 5 is connected with the DCS control system 3; an oxidizing wind algorithm model 51 is embedded in the edge intelligent control integrated machine 5; collecting operation parameters through a desulfurization inlet CEMS 2, and uploading the collected data to a DCS control system 3; the absorption tower discharge pump 8 is arranged at the bottom of the absorption tower and is connected with the absorption tower through a pipeline; the absorption tower discharge pump 8 is also connected to a gypsum cyclone 9 arranged outside the absorption tower through a pipeline; and the dehydrated gypsum is conveyed to the gypsum storehouse 11 through the vacuum belt conveyor 10.

The discharge pump of the absorption tower is mainly used for removing gypsum precipitates in the solution of the absorption tower and ensuring the stable operation of the desulfurization system. If the slurry is not discharged, the device is quickly unable to perform the de-gypsum. The gypsum cyclone is one-stage dewatering to eliminate partial water. The vacuum belt feeder is second grade dewatering device, mainly makes the moisture content of final gypsum be less than 10%, and the gypsum quality is up to standard, can take out, belongs to accessory substance reutilization. Mainly for removing SO by a vacuum belt₂This SO₂Finally, through a series of reactions, gypsum which is a byproduct is formed and then is recycled.

A wet desulphurization Roots blower energy-saving control system method comprises the following steps:

s1-1: installing a measuring device on a flue behind an induced draft fan in front of an absorption tower, and detecting and obtaining data of SO2 concentration, flue gas flow, installation temperature measurement, humidity, oxygen content and pressure entering a desulfurizing tower;

s1-2: installing a measuring device at an outlet at the upper end of the absorption tower, and detecting and obtaining data of SO2 concentration, flue gas flow, temperature, humidity, oxygen content and pressure discharged from an outlet of the desulfurization tower;

the data measured by the measuring device are respectively uploaded to an entrance CEMS through network signals; then the data is transmitted to a DCS control system through a network signal;

s2: the edge intelligent control all-in-one machine acquires the data acquired in the step S1 from the DCS control system, and the oxidation wind algorithm model in the edge intelligent control all-in-one machine is calculated to obtain the air quantity required by the desulfurization and oxidation system; collecting the desulfurization inlet flue gas volume Q1, the desulfurization inlet SO2 concentration C1, the desulfurization outlet flue gas volume Q2 and the desulfurization outlet SO2 concentration C2 in a DCS control system; the collected data are converted numerical values, and the states of the collected data are standard conditions, dry basis and reference oxygen;

removing W1 (Q1 × C1-Q2 × C2)/106 by weight of SO 2;

the required oxygen amount O1 is n multiplied by W1/64 multiplied by 16, n is the oxidation rate, and is 2.5-3.5;

the preliminary value of n is related to the concentration C1 of SO 2;

when the C1 is less than or equal to 2500mg/Nm3, the value of n is 2.5;

when the C1 is more than 2500 and less than or equal to 5000mg/Nm3, the value of n is 3.0;

when C1 is more than 5000mg/Nm3, n takes a value of 3.5;

the required air amount V1 is L1 × O1, and L1 is a coefficient;

s3: performing further calculation through the air amount calculated in the step S2 to obtain the minimum operation frequency required by the operation condition of the on-site desulfurization system;

according to the diameter phi of the pipeline of the oxidation fan, the lowest allowable flow rate is a; obtaining the lowest air volume V2 passing through the oxidation air pipeline; further obtaining a required air volume V20 corresponding to the generated air volume V2;

V2＝3.14×(φ/2)2×a；

v20 ═ V2 × k, k being a coefficient;

the lowest allowable frequency is f1 ═ V20/V0 × 50;

the air volume V0 of the original oxidation fan is 50 Hz. The theoretical calculation running frequency is f-V1/V0 x 50,

when the theoretically calculated running frequency f is lower than the lowest allowable frequency f1, the lowest running frequency is f 1;

when the theoretically calculated running frequency f is higher than the lowest allowable frequency f1, taking f as the lowest running frequency;

s4: the result calculated in the edge intelligent control integrated machine is fed back to the desulfurization DCS system through network signals, and then the signals are transmitted to the oxidation fan frequency converter through the DCS control system and are converted into voltage and current signals to the oxidation fan to realize the adjustment of the oxidation air quantity;

s5: after the edge intelligent control all-in-one machine operates for a period of time, detecting the quality of gypsum; according to the detection result of the gypsum quality, adjusting the oxidation rate n in the step S2, and then curing the oxidation rate n to ensure that the content of calcium sulfite hemihydrate in the gypsum is less than or equal to 0.50%;

the content of calcium sulfite hemihydrate (CaSO3 & 1/2H2O) in the qualified gypsum is less than or equal to 0.50 percent; the quality of the gypsum is mainly determined by the oxidation effect of calcium sulfite hemihydrate (CaSO3 & 1/2H 2O); the better the oxidation effect, the lower the content of calcium sulfite hemihydrate (CaSO3 & 1/2H2O) in the gypsum; the oxidation effect is closely related to the amount of oxidation air blown into the desulfurization tower by the oxidation fan.

Preferably, the method further comprises an operation control protection method; the protection method automatically controls and adjusts the operation of the wet desulphurization oxidation system through modes of PID regulation, filtering, fitting, adaptive learning and the like; when the operation program of the edge intelligent control all-in-one machine is abnormal, the operation program is automatically switched to the original DCS control program, and the safe and stable operation of the desulfurization system is ensured.

Preferably, the detected SO2 concentration, flue gas flow, temperature, humidity, oxygen content and pressure are all online continuous measurement values.

Preferably, the Roots blower is arranged in a one-use-one-standby mode; and the oxidation fan variable-frequency control cabinet gives a signal to the Roots fan.

The normal small unit desulfurization system, the roots fan is one-used one and is equipped with, and the converter gives the signal to the roots fan, can normally operate. But in big unit desulfurization system, three roots's fans share a trunk line, and roots's fan is three uses one and is equipped with, need open two simultaneously, need carry out frequency conversion control to two roots's fans, in order to avoid two roots's fans to robbe the wind, the resistance condition such as big, need carry out synchronous control to two roots's fan's frequency.

When the frequency converter of the oxidation fan is set in the frequency conversion range, the highest output power is the power frequency of the oxidation fan, and the lowest output power is the frequency corresponding to the air quantity of the lowest flow speed of the pipeline of the oxidation fan.

Further, the Roots blower is controlled in three stages:

the first stage, when desulphurization unit preliminary operation, the data that measuring device measured obtained all is little or the distortion, and the data can not be fine guides marginal intelligent control all-in-one to calculate, goes on according to DCS system mode earlier, carries out normal start to the roots's fan.

And in the second stage, when the system normally and stably operates, the mode is switched to an edge intelligent control integrated machine mode, the signal obtained by calculation in the edge intelligent control integrated machine is transmitted to a desulfurization DCS system, and the signal is transmitted to an oxidation fan frequency converter through the desulfurization DCS system and then converted into voltage and current signals to realize the adjustment of the oxidation air volume for the oxidation fan.

And in the third stage, after the edge intelligent control all-in-one machine operates for a period of time, detecting the quality of the gypsum. And adjusting and curing the oxidation multiplying power n of the oxidation fan according to the gypsum quality detection result.

When the frequency converter of the oxidation fan is set in a frequency conversion range, the highest output power is the power frequency of the Roots fan, and the lowest output power is the frequency corresponding to the lowest flow rate of the Roots fan pipeline.

Preferably, two operation modes are set in the desulfurization DCS system; the mode comprises an edge intelligent control all-in-one machine mode and a desulfurization DCS control mode.

In the desulfurization DCS system, can switch the mode (marginal intelligence accuse all-in-one mode, desulfurization DCS control mode), can intervene each link and parameter manually simultaneously, for example frequency, oxidation rate etc. prevent to lose the control to oxidation system under the unusual condition of marginal intelligence accuse all-in-one mode, play the guard action to whole desulfurization system.

The method comprises the following specific implementation steps:

the flue gas enters the absorption tower through the flue after coming out of the induced draft fan 4, and finally the flue gas is discharged from a chimney at the top of the tower; the detection device is arranged on the inlet flue and the flue at the top of the absorption tower; the inlet detection data is uploaded to the inlet CEMS system 2, the outlet detection data is uploaded to the outlet CEMS system 7, and finally the inlet and outlet CEMS signals are transmitted to the DCS control system 3; the DCS control system 3 transmits the frequency signal to the oxidation fan variable-frequency control cabinet 6, and then converts the frequency signal into a voltage signal and a current signal to the Roots fan 1 to realize the adjustment of the oxidation air volume; oxidizing air enters the absorption tower through an oxidizing air pipeline; the edge intelligent control integrated machine 5 is connected with the DCS control system 3 through an OPC or MODBUS communication protocol, calculates the lowest operating frequency of the oxidation fan through a built-in oxidation wind algorithm model 51 by acquiring data of the DCS control system 3, and transmits signals to the DCS control system 3; and then the slurry in the absorption tower is conveyed into a gypsum cyclone 9 through a gypsum discharge pump 8, the slurry with the water content of 50 percent flows through the bottom flow of the gypsum cyclone 9 to a vacuum belt conveyor 10 through the cyclone working principle, and finally the gypsum with the water content of about 10 percent is obtained through the vacuum-pumping principle.

The energy-saving control method of the wet desulphurization Roots blower in the invention is explained below.

When the wet desulphurization preparation is put into operation, the operation is carried out through the DCS, the Roots blower is started, and when the system normally and stably operates, the start and stop of the oxidation blower can be carried out through the DCS (mode one), and the automatic control can also be carried out through the edge intelligent control all-in-one machine mode (mode two); the desulfurization DCS system (the mode I) can be mutually switched with the edge intelligent control all-in-one machine mode (the mode II).

In the edge intelligent control all-in-one machine mode (mode two), an algorithm model system is available, the lowest oxidation fan frequency can be obtained through calculation, the frequency is reversely output to a desulfurization DCS (distributed control system) system (mode one), and the air quantity of an oxidation fan is regulated and controlled. And (3) adjusting the variable of the oxidation rate in the algorithm model by detecting the quality of the final gypsum until the content of the calcium sulfite hemihydrate in the final detected gypsum is lower than a set value, and determining the oxidation wind algorithm model.

The logical block diagram of the regulating and protecting method for the energy-saving control of the wet desulphurization Roots blower is shown in figure 2, which calculates the theoretical oxidation air volume by a chemical formula and actually detects calcium sulfite hemihydrate (CaSO)₃·1/2H₂O) content feedback adjustment together form the control of the air quantity in the whole oxidation process. The specific implementation process is as follows:

(1) when desulphurization unit preliminary operation, the data that measuring device measured and obtained are all on the small side or the distortion, and data can not be fine guides marginal intelligent control all-in-one to calculate, goes on according to DCS system mode earlier, carries out normal start to the roots's fan.

(2) And when the system normally and stably operates, switching to an edge intelligent control all-in-one machine mode. An inlet CEMS detection device is arranged behind the dust remover and in front of the absorption tower, and an outlet CEMS inlet CEMS detection device is arranged behind the desulfurizing towerA device; the dust concentration at the front end of the dust remover is large, and influences the service life of inlet CEMS detection equipment; the device is arranged at the front and the rear of the desulfurizing tower and is used for more accurately detecting the flue gas amount Q1 and SO of the desulfurizing inlet₂Concentration C1, desulfurization outlet flue gas amount Q2 and desulfurization outlet SO₂Concentration C2; the detection data are converted numerical values, the states are standard conditions, dry basis and reference oxygen, and the air quantity required by the desulfurization oxidation system is better calculated.

Wherein, the equation of the oxidation reaction in the wet desulphurization system is mainly as follows:

SO₃ ^2-+1/2O₂——→SO₄ ^2- (1)

HSO₃ ^-+1/2O₂——→SO₃ ^2-+H⁺ (2)

the source is SO in the flue gas₂；

According to equations (1) and (2), theoretically 0.5mol of O₂Oxidizable 1mol SO₂。

W1＝(Q1×C1-Q2×C2)/10⁶； (3)

In the formula: W1-SO removal₂Weight, Kg/h;

q1-desulfurized Inlet flue gas volume, Nm³/h

C1-desulfurization inlet SO₂Concentration, mg/Nm³

Q2-desulfurized Inlet flue gas volume, Nm³/h

C2-desulfurization inlet SO₂Concentration, mg/Nm³

The data are converted numerical values, and the states are standard conditions, dry basis and reference oxygen;

O1＝n×W1/64×16 (4)

o1-oxygen requirement, Kg/h

n is oxidation rate, 2.5-3.5 is selected according to the initial concentration of SO 2;

V1＝O1/0.233/(1-0.01)/1.2875 (5)

v1-space required for theoretical calculationGas volume, Nm³/h

Further, V2 ═ 3.14 × (Φ/2)2 × a (6)

V2-minimum air volume through oxidizing air duct, m³/h

Phi-diameter of pipe, m

a-pipeline flow velocity, m/s;

further, V20 ═ V2 × k (7)

k is a coefficient;

the lowest allowable frequency is f1 ═ V20/V0 × 50.

The air volume V0 of the original oxidation fan is 50 Hz. The theoretical calculation running frequency is f-V1/V0 x 50,

when the theoretically calculated running frequency f is lower than the lowest allowable frequency f1, the lowest running frequency is f 1;

when the theoretically calculated running frequency f is higher than the lowest allowable frequency f1, taking f as the lowest running frequency;

the data measured by the measuring device is firstly uploaded to a CEMS system and then transmitted to a DCS system; the edge intelligent control integrated machine collects data from the desulfurization DCS system, calculates in the edge intelligent control integrated machine, transmits signals to the desulfurization DCS system at last, transmits the signals to the frequency converter of the oxidation fan through the desulfurization DCS system, and converts the signals into voltage and current signals to adjust the oxidation air quantity of the oxidation fan.

(3) After the edge intelligent control all-in-one machine operates for a period of time, the quality of the gypsum is detected. And adjusting and curing the oxidation multiplying power n of the oxidation fan according to the gypsum quality detection result.

When the frequency converter of the oxidation fan is set in the frequency conversion range, the highest output power is the power frequency of the oxidation fan, and the lowest output power is the frequency corresponding to the air quantity of the lowest flow speed of the pipeline of the oxidation fan. The whole calculation process is carried out in an edge intelligent control integrated machine, and the operation of the wet desulphurization oxidation system is automatically controlled and adjusted by modes of PID (proportion integration differentiation) regulation, filtering, fitting, self-adaptive learning and the like; when the operation program of the edge intelligent control all-in-one machine is abnormal, the operation program is automatically switched to the original DCS control program, and the safe and stable operation of the desulfurization system is ensured.

The present invention has been described in relation to the above embodiments, which are only exemplary of the implementation of the present invention. It should be noted that the disclosed embodiments do not limit the scope of the invention. Rather, it is intended that all such modifications and variations be included within the spirit and scope of this invention.