Shotcrete volume control method for SDA semi-dry desulfurization system

Abstract

The present invention discloses a method for controlling the slurry spraying amount of an SDA semi-dry desulfurization system. This method obtains parameters such as the SO2 concentration, inlet flue gas flow rate, inlet flue gas temperature, SO2 concentration in the outlet flue gas, outlet flue gas flow rate, outlet flue gas temperature, solid content of the slurry, correction coefficient, etc. of the system. Under the restrictive condition of the outlet flue gas temperature, the optimal slurry spraying amount is calculated according to the theoretical model to guide the adjustment of the on-site slurry spraying amount, enabling the slurry spraying amount to reach a relatively ideal value, so that the desulfurization effect meets the requirements (ultra-low emission standards for industrial air pollution in iron and steel sintering and pelletizing industries), and at the same time, it can save the enterprise operation cost.

Description

Technical Field

[0001] The invention relates to a method for controlling the spraying amount of an SDA semi-dry desulfurization system, which is used for calculating and controlling the spraying amount and belongs to the technical field of semi-dry desulfurization systems. Background Art

[0002] At present, SO generated by sintering process flue gas 2 Emissions rank first among national industrial SO 2 The second largest emission, accounting for about 11%, is about 1.5-1.8 million tons / year, second only to coal-fired power generation. In order to meet the national ultra-low emission standards for steel sintering and pelletizing industrial air pollution, the sintering flue gas must be desulfurized. Among all desulfurization treatment technologies, SDA semi-dry desulfurization technology is one of the most mature semi-dry flue gas desulfurization technologies in the world.

[0003] SDA semi-dry desulfurization technology utilizes the principle of spray drying. Generally, lime is used as the desulfurizer. The digested slaked lime slurry is atomized into mist particles with a diameter of less than 100μm and a large surface area by a high-speed rotating atomizer at the top of the absorption tower. The flue gas is introduced into the absorption chamber through a gas distributor. After the two are in contact and mixed, intense heat exchange and desulfurization reaction occur. The acidic components in the flue gas are absorbed by the alkali solution, and the water is quickly evaporated. The slurry droplets are heated and dried into powder. The fly ash and part of the dry matter of the reaction products fall into the bottom of the absorption chamber and are discharged. The fine particles enter the dust collector with the treated flue gas and are collected. The treated clean flue gas is discharged through the chimney.

[0004] The SDA desulfurization system mainly injects alkaline slurry into the SO 2 The reaction generates desulfurized ash and discharges it to achieve SO 2 Ultra-low emissions, so the amount of spraying has little effect on SO 2 The removal of SO is crucial. However, there is no clear theoretical basis for the control of the amount of shotcrete at present, and the workers mainly rely on the export of SO 2 The concentration is fed back to manually adjust the front-end spraying volume. This control method is not reasonable in theory to adjust the front end through the back-end data, and it cannot respond to the SO in the inlet flue gas in time. 2 Fluctuations in the spraying volume can easily lead to excessive or insufficient spraying volume, thus affecting the desulfurization effect, reducing the stability of the system operation and increasing the system energy consumption.

[0005] The operator manually adjusts the amount of grouting based on his own experience. Specifically, the operator manually modifies the target value of the grouting amount multiple times based on experience until the desulfurization effect reaches the requirement. The reliability is poor and it is difficult for the system to obtain the optimal grouting amount. If the grouting amount is too small, the required desulfurization effect cannot be achieved; but if the grouting amount is too large, the slurry will not have time to evaporate and dry, which may cause serious ash adhesion on the inner wall of the absorption chamber, agglomeration in the pipeline, and blockage of the pipeline, resulting in poor ash discharge and other problems. Therefore, we need to reasonably control the grouting amount of the system. Summary of the invention

[0006] The purpose of the present invention is to provide a method for controlling the spraying amount of an SDA semi-dry desulfurization system, which can make the spraying amount reach a relatively ideal value, so that the desulfurization effect meets the requirements (ultra-low emission standards for industrial air pollution in steel sintering and pelletizing), while saving the operating costs of the enterprise.

[0007] To achieve the above object, the technical solution of the present invention is:

[0008] Obtain SO in inlet flue gas 2 concentration, inlet flue gas flow, inlet flue gas temperature, and SO in outlet flue gas 2 concentration, outlet flue gas flow, outlet flue gas temperature, slurry solid content, lime activity coefficient;

[0009] According to the inlet flue gas SO 2 concentration, inlet flue gas flow rate, and SO in outlet flue gas 2 The concentration, outlet flue gas flow, slurry solid content, and correction coefficient are used to calculate the theoretical shotcrete volume according to the preset first calculation model;

[0010] According to the inlet flue gas SO 2 concentration, inlet flue gas flow rate, and SO in outlet flue gas 2 Concentration, outlet flue gas flow rate, slurry solid content, inlet flue gas temperature, theoretical shotcrete volume, correction coefficient, calculate the theoretical outlet flue gas temperature according to the estimated second calculation model;

[0011] The theoretical maximum shotcrete volume is calculated based on the outlet flue gas temperature and the estimated third calculation model.

[0012] According to the first formula, calculate the SO in flue gas 2 Removal amount per unit hour; wherein the first formula is:

[0013] TSO 2 =SO 2in *V in -SO 2out *V out

[0014] The theoretical shotcrete volume per unit time is calculated by the second formula, where SO2 Absorption reaction: SO 2 +CaO=CaSO 3 , molar ratio n SO2 :n CaO =1:1, the second formula is:

[0015] M=TSO 2 / 64*56 / S / K

[0016] According to the first and second formulas shown, the theoretical shotcrete volume is calculated according to the first calculation model, wherein the first calculation model is:

[0017] M=(SO 2in *V in -SO 2out *V out ) / 64*56 / S / K

[0018] Among them, SO 2in Indicates the entry SO 2 Volume concentration, V in Indicates the inlet flue gas flow rate per hour, SO 2out Indicates export SO 2 Volume concentration, V out It represents the outlet flue gas flow rate per hour; K represents the lime activity coefficient, and S represents the solid content.

[0019] The inlet flue gas heat is calculated by the third formula, wherein the third formula is:

[0020] Inlet flue gas heat Q in =C gas * gas *V in *T in ;

[0021] The outlet flue gas heat is calculated by the fourth formula, wherein the fourth formula is:

[0022] Exit flue gas heat Q out =C gas * gas *V out *T out ;

[0023] The heat absorbed by the slurry is calculated by the fifth formula, wherein the fifth formula is:

[0024] Slurry absorbs heat Q M =S*C M *M*(T out -T M )+(1-S)*M*(C H2O (T out-T M )+Q H2O )+ΔH*TSO 2 / 64

[0025] According to the third, fourth and fifth formulas shown, the theoretical outlet flue gas temperature is calculated according to the second calculation model, wherein the second calculation model is:

[0026] T out =((C gas * gas *V in *T in +S*C M *M*T M +(1-S)*M*(C H2O *T M -Q H2O )-(ΔH*SO 2in *V in -SO 2out *V out / 64)) / (C gas * gas *V out +S*C M *M+(1-S)*M*C H2O )

[0027] Among them, T in Indicates the inlet flue gas temperature; C gas represents the specific heat capacity of flue gas; ρ gas Indicates smoke density; V in Indicates the smoke flow rate at the smoke inlet; V out Indicates the outlet flue gas flow rate; C M represents the specific heat capacity of lime; C H2O represents the specific heat capacity of water; M represents the theoretical shotcrete volume; T M Indicates the slurry inlet temperature; Q H2O represents the latent heat of vaporization of water per ton of water; ΔH represents SO 2 Molar heat of reaction with CaO; TSO 2 Indicates SO 2 The amount of removal per hour; S represents the solid content.

[0028] According to the second calculation model, the theoretical outlet flue gas temperature is calculated to determine whether the theoretical outlet temperature is greater than 100°C. If the theoretical outlet flue gas temperature is greater than or equal to 100°C, the valve is directly opened for spraying according to the calculated theoretical spraying amount; if the theoretical outlet flue gas temperature is less than 100°C, the theoretical maximum spraying amount is calculated according to the third calculation model for spraying.

[0029] According to the third, fourth and fifth formulas shown, according to the third calculation model, the theoretical maximum shotcrete volume is calculated based on the fact that the flue gas outlet temperature cannot be lower than 100°C, wherein the third calculation model is:

[0030] M max =((C gas * gas *V in *T in -C gas * gas *V out *T out )+(ΔH*SO 2in *V in -SO 2out *V out / 64)) / (S*C M *(T out -T M )+(1-S)*(C H2O (T out -T M )+Q H2O )

[0031] Among them, T in Indicates the inlet flue gas temperature; C gas represents the specific heat capacity of flue gas; ρ gas Indicates smoke density; V in Indicates the smoke flow rate at the smoke inlet; V out Indicates the outlet flue gas flow rate; C M represents the specific heat capacity of lime; C H2O represents the specific heat of water; T M represents the slurry inlet temperature; Q represents the latent heat of vaporization per ton of water; ΔH represents SO 2 Molar heat of reaction with CaO; TSO 2 Indicates SO 2 The removal amount per hour; S represents the solid content; T out Indicates the theoretical outlet flue gas temperature, which is generally a fixed value of 100℃.

[0032] The key point of the present invention is to obtain SO in the inlet flue gas of the system 2 concentration, inlet flue gas flow, inlet flue gas temperature, and SO in outlet flue gas 2 The concentration, outlet flue gas flow rate, outlet flue gas temperature, slurry solid content, correction coefficient and other parameters are used to calculate the optimal shotcrete volume based on the theoretical model under the restrictive link of outlet flue gas temperature to guide the adjustment of on-site shotcrete volume.

[0033] Preferably, according to the first calculation model, the theoretical spraying amount is calculated, and the SO 2Concentration by SO 2 The concentration meter measured the SO in the outlet flue gas. 2 The concentration is set at 35mg / m according to the national ultra-low emission standard for sintering flue gas. 3 The inlet and outlet flue gas flow rates are measured by a flow meter; the lime activity coefficient ranges from 0 to 1.0, and the slurry solid content ranges from 10 to 50%.

[0034] Preferably, if the theoretical maximum spraying amount is used for spraying, alkaline substances, including ammonia water, caustic soda, baking soda, etc., should be sprayed into the flue at the same time to reduce SO in the flue gas. 2 content.

[0035] The advantages of the present invention are:

[0036] By calculating the theoretical flue gas outlet temperature, we can prevent the amount of spraying from being too large, which would lead to too low an outlet temperature and condensation of water vapor, aggravating the serious ash sticking in the subsequent pipelines, causing lumps in the pipelines to block the pipelines and causing problems such as poor ash discharge.

[0037] By calculating the theoretical shotcrete volume, the accuracy of manual adjustment of the shotcrete volume by on-site operators is improved, the shotcrete volume is reasonably controlled, and the optimal operating state of the equipment is ensured.

[0038] By calculating the theoretical maximum shotcrete volume, the system is 2 It provides a theoretical basis for the timing of adding alkaline substances (such as ammonia, baking soda, etc.) under the condition that ultra-low emissions cannot be controlled.

[0039] The establishment of the SDA semi-dry system shotcrete quantity control model can make the shotcrete quantity reach a relatively ideal value, so that the desulfurization effect meets the requirements (ultra-low emission standards for industrial air pollution in steel sintering and pelletizing), while saving the company's operating costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0041] Figure 1 The present invention is a flow chart of the method for controlling the spraying amount of the SDA desulfurization system. DETAILED DESCRIPTION

[0042] Please refer to the attached Figure 1 , Figure 1 Flow chart of the method for controlling the amount of slurry sprayed in the SDA desulfurization system provided in the embodiment of the present invention. The method for controlling the amount of slurry sprayed in the SDA desulfurization system of the present invention can be applied to a controller, wherein the controller is a PLC (Programmable Logic Controller). The following embodiments are specifically described by taking PLC as an example.

[0043] Example 1

[0044] Step S101, input

[0045] SO in inlet flue gas 2 Concentration: 600mg / m 3

[0046] Inlet flue gas flow: 1.2 million m 3 / h

[0047] SO in outlet flue gas 2 Concentration: 35mg / m 3

[0048] Outlet flue gas flow: 1.25 million m 3 / h

[0049] Slurry solid content: 18%

[0050] Lime activity coefficient: 0.1

[0051] Step S102, calculation formula: First calculation model

[0052] According to the first formula, calculate the SO in flue gas 2 Removal amount per unit hour; wherein, the first formula is

[0053] TSO 2 =SO 2in *V in -SO 2out *V out

[0054] The theoretical shotcrete volume per unit time is calculated by the second formula, where SO 2 Absorption reaction:

[0055] SO 2 +CaO=CaSO 3 , molar ratio n SO2 :n CaO =1:1, the second formula is:

[0056] M=TSO 2 / 64*56 / S / K

[0057] According to the first and second formulas shown, the theoretical outlet flue gas temperature is calculated according to the first calculation model, wherein the first calculation model is:

[0058] M=(SO 2in *V in -SO 2out *V out) / 64*56 / S / K

[0059] Among them, SO 2in Indicates the entry SO 2 Volume concentration, V in Indicates the inlet flue gas flow rate per hour, SO 2out Indicates export SO 2 Volume concentration, V out It represents the outlet flue gas flow rate per unit hour; K represents the lime activity coefficient, and S represents the solid content.

[0060] Step S103, output: calculated by the first calculation model, the theoretical shotcrete volume is 32.87 t / h.

[0061] Step S104, input

[0062] Flue gas temperature 140℃

[0063] Theoretical shotcrete volume: 32.87t / h

[0064] Step S105, calculation formula: Second calculation model

[0065] The inlet flue gas heat is calculated by the third formula, wherein the third formula is:

[0066] Inlet flue gas heat Q in =C gas * gas *V in *T in ;

[0067] The outlet flue gas heat is calculated by the fourth formula, wherein the fourth formula is:

[0068] Exit flue gas heat Q out =C gas * gas *V out *T out ;

[0069] The heat absorbed by the slurry is calculated by the fifth formula, wherein the fifth formula is:

[0070] Slurry absorbs heat Q M =S*C M *M*(T out -T M )+(1-S)*M*(C H2O (T out -T M )+Q H2O )+ΔH*

[0071] TSO 2 / 64;

[0072] According to the third, fourth and fifth formulas shown, the theoretical outlet flue gas temperature is calculated according to the second calculation model, wherein the second calculation model is:

[0073] T out =((C gas * gas *V in *T in +S*C M *M*T M +(1-S)*M*(C H2O *T M -Q H2O )-(ΔH*SO 2in *V in -SO 2out *V out / 64)) / (C gas * gas *V out +S*C M *M+(1-S)*M*C H2O )

[0074] Among them, T in Indicates the inlet flue gas temperature; C gas represents the specific heat capacity of flue gas; ρ gas Indicates smoke density; V in Indicates the smoke flow rate at the smoke inlet; V out Indicates the outlet flue gas flow rate; C M represents the specific heat capacity of lime; C H2O represents the specific heat capacity of water; M represents the theoretical shotcrete volume; T M Indicates the slurry inlet temperature; Q H2O represents the latent heat of vaporization of water per ton of water; ΔH represents SO 2 Molar heat of reaction with CaO; TSO 2 Indicates SO 2 The amount of removal per hour; S represents the solid content.

[0075] Step S106, output: After calculation by the second calculation model, the theoretical flue gas outlet temperature is 102.7°C.

[0076] Step S107, judging: the theoretical outlet flue gas temperature is greater than 100°C.

[0077] Step S108, output: target shotcrete volume = theoretical shotcrete volume = 32.87 t / h.

[0078] Example 2

[0079] Step S201, input

[0080] SO in inlet flue gas2 Concentration: 800mg / m 3

[0081] Inlet flue gas flow: 1.2 million m 3 / h

[0082] SO in outlet flue gas 2 Concentration: 35mg / m 3

[0083] Outlet flue gas flow: 1.25 million m 3 / h

[0084] Slurry solid content: 18%

[0085] Lime activity coefficient: 0.12

[0086] Step S202, calculation formula: First calculation model

[0087] According to the first formula, calculate the SO in flue gas 2 Removal amount per unit hour; wherein the first formula is:

[0088] TSO 2 =SO 2in *V in -SO 2out *V out

[0089] The theoretical shotcrete volume per unit time is calculated by the second formula, where SO 2 Absorption reaction:

[0090] SO 2 +CaO=CaSO 3 , molar ratio n SO2 :n CaO =1:1, the second formula is:

[0091] M=TSO 2 / 64*56 / S / K

[0092] According to the first and second formulas shown, the theoretical outlet flue gas temperature is calculated according to the first calculation model, wherein the first calculation model is:

[0093] M=(SO 2in *V in -SO 2out *V out ) / 64*56 / S / K

[0094] Among them, SO 2in Indicates the entry SO 2 Volume concentration, V in Indicates the inlet flue gas flow rate per hour, SO2out Indicates export SO 2 Volume concentration, V out It represents the outlet flue gas flow rate per unit hour; K represents the lime activity coefficient, and S represents the solid content.

[0095] Step S203, output: calculated by the first calculation model, the theoretical shotcrete volume is 37.27 t / h.

[0096] Step S204, input

[0097] Flue gas temperature 140℃

[0098] Theoretical shotcrete volume: 37.27t / h

[0099] Step S205, calculation formula: Second calculation model

[0100] The inlet flue gas heat is calculated by the third formula, wherein the third formula is:

[0101] Inlet flue gas heat Q in =C gas * gas *V in *T in ;

[0102] The outlet flue gas heat is calculated by the fourth formula, wherein the fourth formula is:

[0103] Exit flue gas heat Q out =C gas * gas *V out *T out ;

[0104] The heat absorbed by the slurry is calculated by the fifth formula, wherein the fifth formula is:

[0105] Slurry absorbs heat Q M =S*C M *M*(T out -T M )+(1-S)*M*(C H2O (T out -T M )+Q H2O )+ΔH*

[0106] TSO 2 / 64;

[0107] According to the third, fourth and fifth formulas shown, the theoretical outlet flue gas temperature is calculated according to the second calculation model, wherein the second calculation model is:

[0108] T out =((Cgas * gas *V in *T in +S*C M *M*T M +(1-S)*M*(C H2O *T M -Q H2O )-(ΔH*SO 2in *V in -SO 2out *V out / 64)) / (C gas * gas *V out +S*C M *M+(1-S)*M*C H2O )

[0109] Among them, T in Indicates the inlet flue gas temperature; C gas represents the specific heat capacity of flue gas; ρ gas Indicates smoke density; V in Indicates the smoke flow rate at the smoke inlet; V out Indicates the outlet flue gas flow rate; C M represents the specific heat capacity of lime; C H2O represents the specific heat capacity of water; M represents the theoretical shotcrete volume; T M represents the slurry inlet temperature; Q represents the latent heat of vaporization per ton of water; ΔH represents SO 2 Molar heat of reaction with CaO; TSO 2 Indicates SO 2 The amount of solid removed per hour; S represents the solid content; K represents the activity coefficient of lime.

[0110] Step S206, output: calculated by the second calculation model, the theoretical flue gas outlet temperature is 98.70°C.

[0111] Step S207, judging: the theoretical outlet flue gas temperature is less than 100°C.

[0112] Step S208, input: theoretical outlet flue gas temperature = 100°C.

[0113] Step S209, calculation formula: The third calculation model

[0114] The inlet flue gas heat is calculated by the third calculation model, wherein the third formula is:

[0115] M max =((C gas * gas *V in *T in -Cgas * gas *V out *T out )+(ΔH*SO 2in *V in -SO 2out *V out / 64)) / (S*C M *(T out -T M )+(1-S)*(C H2O (T out -T M )+Q H2O )

[0116] Among them, T in Indicates the inlet flue gas temperature; C gas represents the specific heat capacity of flue gas; ρ gas Indicates smoke density; V in Indicates the smoke flow rate at the smoke inlet; V out Indicates the outlet flue gas flow rate; C M represents the specific heat capacity of lime; C H2O represents the specific heat of water; T M represents the slurry inlet temperature; Q represents the latent heat of vaporization per ton of water; ΔH represents SO 2 Molar heat of reaction with CaO; TSO 2 Indicates SO 2 The removal amount per hour; S represents the solid content; T out Indicates the theoretical outlet flue gas temperature, which is generally a fixed value of 100℃.

[0117] Step S210, output: calculated by the third calculation model, the target shotcrete volume = the theoretical maximum shotcrete volume is 35.80 t / h, and at the same time, alkaline substances are sprayed into the flue.

[0118] Example 3

[0119] Step S301, input

[0120] SO in inlet flue gas 2 Concentration: 600mg / m 3

[0121] Inlet flue gas flow: 1.2 million m 3 / h

[0122] SO in outlet flue gas 2 Concentration: 35mg / m 3

[0123] Outlet flue gas flow: 1.25 million m 3 / h

[0124] Slurry solid content: 15%

[0125] Lime activity coefficient: 0.1

[0126] Step S302, calculation formula: First calculation model

[0127] According to the first formula, calculate the SO in flue gas 2 Removal amount per unit hour; wherein the first formula is:

[0128] TSO 2 =SO 2in *V in -SO 2out *V out

[0129] The theoretical shotcrete volume per unit time is calculated by the second formula, where SO 2 Absorption reaction:

[0130] SO 2 +CaO=CaSO 3 , molar ratio n SO2 :n CaO =1:1, the second formula is:

[0131] M=TSO2 / 64*56 / S / K

[0132] According to the first and second formulas shown, the theoretical outlet flue gas temperature is calculated according to the first calculation model, wherein the first calculation model is:

[0133] M=(SO 2in *V in -SO 2out *V out ) / 64*56 / S / K

[0134] Among them, SO 2in Indicates the entry SO 2 Volume concentration, V in Indicates the inlet flue gas flow rate per hour, SO 2out Indicates export SO 2 Volume concentration, V out It represents the outlet flue gas flow rate per unit hour; K represents the lime activity coefficient, and S represents the solid content.

[0135] Step S303, output: calculated by the first calculation model, the theoretical shotcrete volume is 39.45 t / h.

[0136] Step S304, input flue gas temperature 145°C, theoretical spraying volume 39.45t / h

[0137] Step S305, calculation formula: Second calculation model

[0138] The inlet flue gas heat is calculated by the third formula, wherein the third formula is:

[0139] Inlet flue gas heat Q in =C gas * gas *V in *T in ;

[0140] The outlet flue gas heat is calculated by the fourth formula, wherein the fourth formula is:

[0141] Exit flue gas heat Q out =C gas * gas *V out *T out ;

[0142] The heat absorbed by the slurry is calculated by the fifth formula, wherein the fifth formula is:

[0143] Slurry absorbs heat Q M =S*C M *M*(T out -T M )+(1-S)*M*(C H2O (T out -T M )+Q H2O )+ΔH*

[0144] TSO 2 / 64;

[0145] According to the third, fourth and fifth formulas shown, the theoretical outlet flue gas temperature is calculated according to the second calculation model, wherein the second calculation model is:

[0146] T out =((C gas * gas *V in *T in +S*C M *M*T M +(1-S)*M*(C H2O *T M -Q H2O )-(ΔH*SO 2in *V in -SO 2out *V out / 64)) / (C gas * gas *V out +S*C M*M+(1-S)*M*C H2O )

[0147] Among them, T in Indicates the inlet flue gas temperature; C gas represents the specific heat capacity of flue gas; ρ gas Indicates smoke density; V in Indicates the smoke flow rate at the smoke inlet; V out Indicates the outlet flue gas flow rate; C M represents the specific heat capacity of lime; C H2O represents the specific heat capacity of water; M represents the theoretical shotcrete volume; T M represents the slurry inlet temperature; Q represents the latent heat of vaporization per ton of water; ΔH represents SO 2 Molar heat of reaction with CaO; TSO 2 Indicates SO 2 The amount of removal per hour; S represents the solid content.

[0148] Step S306, output: After calculation by the second calculation model, the theoretical flue gas outlet temperature is 95.61°C.

[0149] Step S307, judging: the theoretical outlet flue gas temperature is less than 100°C.

[0150] Step S308, input: theoretical outlet flue gas temperature = 100°C.

[0151] Step S309, calculation formula: the third calculation model

[0152] The inlet flue gas heat is calculated by the third calculation model, wherein the third formula is:

[0153] M max =((C gas * gas *V in *T in -C gas * gas *V out *T out )+(ΔH*SO 2in *V in -SO 2out *V out / 64)) / (S*C M *(T out -T M )+(1-S)*(C H2O (T out -T M )+Q H2O )

[0154] Among them, T inIndicates the inlet flue gas temperature; C gas represents the specific heat capacity of flue gas; ρ gas Indicates smoke density; V in Indicates the smoke flow rate at the smoke inlet; V out Indicates the outlet flue gas flow rate; C M represents the specific heat capacity of lime; C H2O represents the specific heat of water; T M represents the slurry inlet temperature; Q represents the latent heat of vaporization per ton of water; ΔH represents SO 2 Molar heat of reaction with CaO; TSO 2 Indicates SO 2 The removal amount per hour; S represents the solid content; T out Indicates the theoretical outlet flue gas temperature, which is generally a fixed value of 100℃.

[0155] Step S210, output: calculated by the third calculation model, the target shotcrete volume = the theoretical maximum shotcrete volume is 34.62 t / h, and at the same time, alkaline substances are sprayed into the flue.

[0156] The above embodiments do not limit the present invention in any way, and any technical solutions obtained by equivalent replacement or equivalent transformation fall within the protection scope of the present invention.

Claims

1. Shotcrete volume control method for SDA semi-dry desulfurization system, Features The following steps are involved: Step S1: Obtain SO in inlet flue gas 2 concentration, inlet flue gas flow, inlet flue gas temperature, and SO in outlet flue gas 2 concentration, outlet flue gas flow, outlet flue gas temperature, slurry solid content, lime activity coefficient; Step S2: Calculate the SO in the flue gas using the first formula 2 Removal amount per unit hour; wherein the first formula is: TSO 2 =SO 2in *V in -SO 2out *V out Step S3: Calculate the theoretical shotcrete volume per unit time by the second formula, where SO 2 Absorption reaction: SO 2 +CaO=CaSO 3 , molar ratio n SO2 :n CaO =1:1, the second formula is: M=TSO 2 / 64*56 / S / K Step S4: Calculate the theoretical shotcrete volume according to the first and second formulas and the first calculation model, wherein the first calculation model is: M=(SO 2in *V in -SO 2out *V out ) / 64*56 / S / K Among them, SO 2in Indicates the entry SO 2 Volume concentration, V in Indicates the inlet flue gas flow rate per hour, SO 2out Indicates export SO 2 Volume concentration, V out It indicates the outlet flue gas flow rate per hour; K indicates the lime activity coefficient, S indicates the solid content, and M indicates the theoretical shotcrete volume; Step S5: Calculate the inlet flue gas heat by a third formula, wherein the third formula is: Inlet flue gas heat Q in =C gas *ρ gas *V in *T in ; Step S6: Calculate the outlet flue gas heat by the fourth formula, wherein the fourth formula is: Exit flue gas heat Q out =C gas *ρ gas *V out *T out ; Step S7: Calculate the heat absorbed by the slurry using the fifth formula, wherein the fifth formula is: Slurry absorbs heat Q M =S*C M *M*(T out -T M )+(1-S)*M*(C H2O (T out -T M )+Q H2O )+ΔH*TSO 2 / 64 Step S8: Calculate the theoretical outlet flue gas temperature according to the third formula, the fourth formula, and the fifth formula and the second calculation model, wherein the second calculation model is: T out =((C gas *ρ gas *V in *T in +S*C M *M*T M +(1-S)*M*(C H2O *T M -Q H2O )-(ΔH*SO 2in *V in - SO 2out *V out / 64)) / (C gas *ρ gas *V out +S*C M *M+(1-S)*M*C H2O ) Among them, T in Indicates the inlet flue gas temperature; C gas represents the specific heat capacity of flue gas; ρ gas Indicates smoke density; V in Indicates the smoke flow rate at the smoke inlet; V out Indicates the outlet flue gas flow rate; C M represents the specific heat capacity of lime; C H2O represents the specific heat capacity of water; M represents the theoretical shotcrete volume; T M Indicates the slurry inlet temperature; Q H2O represents the latent heat of vaporization of water; ΔH represents SO 2 Molar heat of reaction with CaO; TSO 2 Indicates SO 2 The removal amount per hour; S represents the solid content, T out Indicates the theoretical outlet flue gas temperature; Step S9: determine whether the theoretical outlet flue gas temperature is greater than 100°C; Step S91: if the theoretical outlet flue gas temperature is greater than or equal to 100° C., directly open the valve to spray according to the calculated theoretical spraying amount; Step S92: If the theoretical outlet flue gas temperature is less than 100°C, the theoretical maximum shotcrete volume M is calculated according to the third calculation model. max Shotcrete is performed, wherein the third calculation model is: M max =((C gas *ρ gas *V in *T in -C gas *ρ gas *V out *T out )+(ΔH*SO 2in *V in -SO 2out *V out / 64)) / (S*C M * (T out -T M )+(1-S)*(C H2O (T out -T M )+Q H2O ) Among them, T in Indicates the inlet flue gas temperature; C gas represents the specific heat capacity of flue gas; ρ gas Indicates smoke density; V in Indicates the smoke flow rate at the smoke inlet; V out Indicates the outlet flue gas flow rate; C M represents the specific heat capacity of lime; C H2O represents the specific heat of water; T M Indicates the slurry inlet temperature; Q H2O represents the latent heat of vaporization of water; ΔH represents SO 2 Molar heat of reaction with CaO; TSO 2 Indicates SO 2 The amount of removal per hour; S represents the solid content.

2. The method for controlling the amount of spraying in the SDA semi-dry desulfurization system according to claim 1, Features: According to the first calculation model, the theoretical spraying amount is calculated, and the SO 2 Concentration by SO 2 The concentration meter measured the SO in the outlet flue gas. 2 The concentration is set at 35mg / m according to the national ultra-low emission standard for sintering flue gas. 3 The inlet flue gas flow rate and the outlet flue gas flow rate are measured by a flow meter; the lime activity coefficient ranges from 0 to 1.0, and the slurry solid content ranges from 10 to 50%.

3. The method for controlling the spraying amount of the SDA semi-dry desulfurization system according to claim 1, Features: When spraying is carried out according to the theoretical maximum spraying amount, alkaline substances are sprayed into the flue at the same time.

4. The method for controlling the amount of spraying in the SDA semi-dry desulfurization system according to claim 3, Features: The alkaline substances include ammonia water, caustic soda and baking soda.

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