CN103472189A - Measuring method of kinetic parameter change rules of after-service SCR (selective catalytic reduction) denitrification system catalyst - Google Patents

Abstract

The invention relates to a measuring method of kinetic parameter change rules of an after-service SCR (selective catalytic reduction) denitrification system catalyst, which comprises the following steps: establishing an SCR catalyst activity detection experiment table, cutting off a test sample block from the whole in-service catalyst block in site, putting the test sample block in a reactor, and setting experimental parameters for all experiments, including reactor internal temperature, experiment gas introduction amount and ammonia-nitrogen ratio; and simulating the chemical reaction process of the in-service SCR denitrification system catalyst, establishing a chemical reaction model of the catalyst in the reactor, calculating the kinetic parameters of the catalyst, and fitting to obtain a kinetic parameter change rule curve chart for predicting the kinetic parameter change rules of the catalyst. The technique provided by the invention can provide technical support for establishment of a power plant SCR denitrification system operation regulation scheme.

Description

The measuring method of kinetic parameter Changing Pattern after the military service of SCR denitrating system catalyzer

Technical field

The present invention relates to the electric power project engineering field, particularly relate to the measuring method of the rear kinetic parameter Changing Pattern of a kind of SCR denitrating system catalyzer military service.

Background technology

The selective catalytic reduction denitration technology is mainly with TiO ₂v for carrier ₂o ₅the base industrial catalyst, comprise V ₂o ₅/ TiO ₂, V ₂o ₅/ TiO ₂-SiO ₂, V ₂o ₅-WO3/TiO ₂and V ₂o ₅-MoO ₃/ TiO ₂, its operating temperature is between 280-420 ℃, and denitration efficiency can reach more than 85%, can effectively reduce discharged nitrous oxides, meets the environmental requirement of increasingly stringent, in thermal power generation, is widely applied.The Recent Progresses In The Development of low temperature SCR denitration catalyst is very fast in recent years, has formed and take activated charcoal as carrier, with V ₂o ₅, Fe ₂o ₃and MnO _xdeng the various catalyzer that are active component, but these catalyzer are all not yet through the industry checking.At home, in order to meet more and more stricter NO _xemission standard, the SCR denitration technology has become the mainstream technology that thermal power plant's oxides of nitrogen is controlled.

Catalyzer is the core of the SCR of power plant flue gas denitrification system, it accounts for 1/3 of its investment, the selection of catalyst structure and composition is most important to the power plant safety economical operation, and in operational process, the periodic replacement expense needed due to the inefficacy of its catalyzer accounts for the major part of operating cost, after the SCR denitrating system is installed, also can bring impact to structural design and the safety and economic operation of steam generator system.Therefore, need the denitration performance Changing Pattern of catalyzer in the on-the-spot military service process of prediction, the formulation that moves regulation scheme for the SCR of power plant denitrating system provides the guidance foundation.

Summary of the invention

Based on this, the measuring method of kinetic parameter Changing Pattern after being necessary to provide a kind of SCR denitrating system catalyzer to be on active service, thus can provide foundation for the formulation of the SCR of power plant denitrating system operation regulation scheme.

After a kind of SCR denitrating system catalyzer military service, the measuring method of kinetic parameter Changing Pattern, comprise the steps:

Build SCR catalyst activity test experience platform, this experiment table comprises:

The trace water pump, carburetor, mixer, primary heater, add electrothermal stove, NO gas standard gas cylinder, O ₂gas standard gas cylinder, N ₂gas standard gas cylinder, NH ₃gas standard gas cylinder, reactor and flue gas analyzer; Wherein, micro-water pump, carburetor, primary heater, reactor connect by conduit; Mixer connects NO gas standard gas cylinder, O by conduit ₂gas standard gas cylinder and N ₂the gas standard gas cylinder, access respectively NO gas, O ₂gas and N ₂gas; Reactor connects NH by conduit ₃the gas standard gas cylinder, access NH ₃gas; Carburetor produces H ₂o gas, reactor is placed in and adds electrothermal stove;

The experimental implementation process is as follows:

Cut out coupon the monoblock catalyzer of being on active service from scene, coupon is placed in reactor, set the experiment parameter of each experiment, comprising: inside reactor temperature, experimental gas import volume and ammonia nitrogen ratio;

During experiment, first pass into O ₂gas and N ₂gas, start and to add electrothermal stove, with constant heating rate, inside reactor is heated to design temperature, until temperature, keep after stable passing into NO gas, after the concentration stabilize of NO, record flue gas analyzer record the NO gas concentration; Then pass into NH3 gas and reacted in reactor, after the NO gas concentration after question response tends towards stability, record flue gas analyzer record the NO gas concentration;

Set up the Chemical Reaction Model of catalyst reactor, NO gas concentration parameter according to record, the structural parameters of catalyzer and Chemical Reaction Model are calculated the kinetic parameter of catalyzer, respectively each ammonia nitrogen than under kinetic parameter corresponding to each temperature of matching, obtain the kinetic parameter variation rule curve figure of catalyzer before and after being on active service.

The measuring method of kinetic parameter Changing Pattern after above-mentioned SCR denitrating system catalyzer military service, mode based on experiment and calculating coupling, catalyst chemical course of reaction by the in commission SCR denitrating system of simulated field, then calculate the kinetic parameter of catalyzer according to the related experiment data, matching obtains kinetic parameter variation rule curve figure again, be used for predicting the kinetic parameter Changing Pattern of catalyzer, thereby can provide technical support for the formulation of the SCR of power plant denitrating system operation regulation scheme.

The accompanying drawing explanation

The structural representation that Fig. 1 is SCR catalyst activity test experience platform;

Figure 2 shows that the schematic diagram of the reactor of fixed bed integration;

The fitted figure that Fig. 3 is the kinetic parameter before the corrugated plate catalyzer is on active service;

The fitted figure that Fig. 4 is the kinetic parameter after the corrugated plate catalyzer is on active service.

Embodiment

After below in conjunction with accompanying drawing, SCR denitrating system catalyzer of the present invention being on active service, the embodiment of the measuring method of kinetic parameter Changing Pattern is described in detail.

Structural representation shown in Figure 1, that Fig. 1 is SCR catalyst activity test experience platform, this experiment table comprises:

The trace water pump 101, carburetor 102, mixer 103, primary heater 104, add electrothermal stove 106, reactor 105, NO gas standard gas cylinder 109, O ₂gas standard gas cylinder 110, N ₂gas standard gas cylinder 108, NH ₃gas standard gas cylinder 111 and flue gas analyzer 107; Mixer connects NO gas standard gas cylinder 109, O by conduit ₂gas standard gas cylinder 110 and N ₂gas standard gas cylinder 108, access respectively NO gas, O ₂gas and N ₂gas; Reactor 105 connects NH by conduit ₃gas standard gas cylinder 111, access NH ₃gas; Reactor 105 is placed in and adds electrothermal stove 106.

Its specific works principle is as follows:

By NO gas standard gas cylinder 109, O ₂gas standard gas cylinder 110, N2 gas standard gas cylinder 108 and NH ₃gas standard gas cylinder 111 imports respectively NO gas, N ₂gas, O ₂gas and NH ₃gas, and measure the gaseous mass flow through.Carburetor 102 imports H ₂o, wherein reacting gas is NO, O ₂and NH ₃, N ₂for carrier, H ₂o is vaporized by micro-water pump 101 suction carburetors 102, and the effect of mixer 103 is by NO gas, N ₂gas and O ₂gas fully mixes, and mixed gas passes into primary heater 104 and is heated to 200 ℃ of left and right, NH ₃add before adding electrothermal stove 106, enter reactor 105 together with mixed gas, before experiment, the monoblock catalyzer is cut out to the coupon of 50mm * 50mm * 35mm, be positioned on the specimen holder 115 at reactor 105 centers.Electric furnace is comprised of four sections heating, makes experimental gas be heated to require temperature, and keeps reactor 105 temperature even.Reacting gas reacts in catalyzer a, the temperature of catalyzer a is measured by stretching into catalyst center E type thermopair, and the temperature that will measure catalyzer a realizes showing, by regulating furnace temperature, make the temperature of reactor 105 inner catalyst a reach setting value, reacted flue gas, successively lowered the temperature by 112 pairs of reacted flue gases of condenser, and 113 pairs of reacted flue gases of exsiccator carry out drying processing, then carry out flue gas analysis by flue gas analyzer 107.

The experimental implementation process is as follows:

Cut out coupon the monoblock catalyzer of being on active service from scene, coupon is placed in reactor, wherein, the catalyzer of experiment comprises: the honeycombed catalyst of the corrugated plate catalyzer of new corrugated plate catalyzer and military service 40200h, new honeycombed catalyst and military service 20000h.

Set the experiment parameter of each experiment, comprising: inside reactor temperature, experimental gas import volume and ammonia nitrogen ratio.Concrete, in described experiment, the inside reactor temperature is respectively 290 ℃, 320 ℃, 350 ℃, 380 ℃; In experiment, gas is NO gas 300ppm, O ₂gas is 5%, H ₂o gas is 10%, and remainder is N ₂gas; The ammonia nitrogen ratio is respectively 0.5,0.8,1.1.

During experiment, first pass into O ₂gas and N ₂gas, start and to add electrothermal stove, with constant heating rate, inside reactor is heated to design temperature, until temperature, keep after stable passing into NO gas, after the concentration stabilize of NO, record flue gas analyzer record the NO gas concentration; Then pass into NH ₃gas is reacted in reactor, after the NO gas concentration after question response tends towards stability, record flue gas analyzer record the NO gas concentration.

In one embodiment, after experimental data is stablized 30 minutes, record flue gas analyzer record NO gas concentration data, every kind of catalyzer repeats twice experiment, and record data are the mean value of getting twice experiment, can guarantee reliability and the accuracy of experimental data.

After above-mentioned experimentation, set up the Chemical Reaction Model of catalyst reactor, NO gas concentration parameter according to record, the structural parameters of catalyzer and Chemical Reaction Model are calculated the kinetic parameter of catalyzer, respectively each ammonia nitrogen than under kinetic parameter corresponding to each temperature of matching, obtain the kinetic parameter variation rule curve figure of catalyzer before and after being on active service.

In one embodiment, detailed process is as follows:

Shown in figure 2, Figure 2 shows that the schematic diagram of the reactor of fixed bed integration, suppose that flow of flue gas is the one dimension plug flow, NO in flue gas _xonly consider the main reaction formula of NO, set up the governing equation of element of volume, as formula (1):

$R_{\mathrm{NO}}(1-{\mathrm{\ϵ}}_B)\·A\·\mathrm{dl}=A\·u\·C_{\mathrm{NO}}^0{\mathrm{dx}}_{\mathrm{NO}}---\left(1\right)$

In formula, R _nOnO reaction rate (mol/m for per volume of catalyst ³-cat/s), ε _bfor the porosity of beds, A is catalyst inlet sectional area (m ²), the length that l is catalyzer, the superficial velocity that u is flue gas (m/s),

for the reactor inlet volumetric molar concentration (mol/m3) of NO, x _nOconversion ratio for NO.

When the ammonia nitrogen ratio is greater than 1, reaction rate equation adopts the first order reaction rate equation, as formula (2).

R _NO=K _NOC _NO (2)

In formula, K _nOfor the apparent reaction rate constant (1/s) of NO, C _nOvolumetric molar concentration (mol/m for NO ³).

When the ammonia nitrogen ratio is less than 1, the reaction rate equation formula is suc as formula (3).

$R_{\mathrm{NO}}=K_{\mathrm{NO}}{C}_{\mathrm{NO}}{\mathrm{\θ}}_{{\mathrm{NH}}_3}---\left(3\right)$

In formula,

for NH ₃coverage rate, i.e. NH ₃the active sites that is adsorbed on catalyst surface accounts for the ratio of the total active sites of catalyst surface.

K _nOadopt the Arrhenius equation,

K _NO=Aexp(-E/RT) (4)

In formula, the pre-exponential factor (1/s) that A is the NO reaction, the energy of activation (J/mol) that E is the NO reaction, R is mol gas constant (J/mol/K), and its value is 8.314J/mol/K, and T is thermodynamic temperature.

And the coverage rate expression formula of NH3 is:

${\mathrm{\θ}}_{{\mathrm{NH}}_3}=\frac{K_{{\mathrm{NH}}_3}\·C_{{\mathrm{NH}}_3}}{1+K_{{\mathrm{NH}}_3}\·C_{{\mathrm{NH}}_3}}---\left(5\right)$

In formula,

for NH ₃rate of adsorption constant (m ³/ mol), for NH ₃volumetric molar concentration (mol/m ³).

Right the same Arrhenius equation that adopts:

$K_{{\mathrm{NH}}_3}=A_{{\mathrm{NH}}_3}\exp (-H_{{\mathrm{NH}}_3}/\mathrm{RT})---\left(6\right)$

In formula,

for NH ₃the pre-exponential factor (1/s) of rate of adsorption constant,

for NH ₃the energy of activation (J/mol) of rate of adsorption constant.

And the conversion ratio of NO can be expressed as:

$x_{\mathrm{NO}}=\frac{C_{\mathrm{NO}}^0-C_{\mathrm{NO}}}{C_{\mathrm{NO}}^0}---\left(7\right)$

NH by control volume ₃concentration

be expressed as:

$C_{{\mathrm{NH}}_3}=C_{{\mathrm{NH}}_3}^0-(C_{\mathrm{NO}}^0-C_{\mathrm{NO}})---\left(8\right)$

Ammonia nitrogen is defined as than α:

$\mathrm{\α}=C_{{\mathrm{NH}}_3}^0/C_{\mathrm{NO}}^0---\left(9\right)$

By formula (2), formula (4), formula (7) and formula (8) substitution governing equation (1) integration, can obtain the ammonia nitrogen ratio and be greater than 1 o'clock integral expression:

$K_{\mathrm{NO}}=\frac{-u\ln (1-\mathrm{\η})}{(1-{\mathrm{\ϵ}}_B)L}---\left(10\right)$

In formula,

the width that L is the catalyzer cross section.

Formula (4), to formula (9) substitution governing equation (1) integration, can be obtained to ammonia nitrogen than the integral expression that is less than at 1 o'clock:

$\frac{u}{C_{\mathrm{NO}}^0(\mathrm{\α}-1)}\ln \left(\frac{\mathrm{\α}-\mathrm{\η}}{1-\mathrm{\η}}\right)-\frac{u}{C_{\mathrm{NO}}^0(\mathrm{\α}-1)}\ln \mathrm{\α}=(1-{\mathrm{\ϵ}}_B)K_{\mathrm{NO}}\·K_{{\mathrm{NH}}_3}L+u{K}_{{\mathrm{NH}}_3}\·\ln (1-\mathrm{\η})---\left(11\right)$

In formula,

the width that L is the catalyzer cross section.

In this process, the kinetic parameter that ask for be A, E in formula (4) and formula (6),

with

according to formula (4) and formula (6), at a given temperature, K _nOand K _nH3it is all definite value.Being greater than at 1 o'clock at the ammonia nitrogen ratio adopts formula (10) to ask for the K at each temperature _nOvalue, suppose the K to fixed temperature _nOnot with ammonia nitrogen than changing, then, employing formula (11) is asked at the ammonia nitrogen ratio and is less than at 1 o'clock, the K that each temperature is corresponding _nH3value, remake ln (K _nO)-1/RT and ln (K _nH3the linear fit of)-1/RT, now, slope is K _nOor K _nH3energy of activation, intercept is exactly K _nOor K _nH3the natural logarithm value of pre-exponential factor.

The apparent kinetics parameter is that the impact of diffusion couple reaction rate is attached on kinetic parameter, and interior external diffusion affected to equivalence in the apparent kinetics parameter.

For example, at the ammonia nitrogen ratio, be 1.1 o'clock, calculate temperature and be the K of 290 ℃, 320 ℃ and 350 ℃ _nO, then at ammonia nitrogen, than 0.8 o'clock, keep K corresponding to each temperature _nOconstant, adopt and calculate again the K that temperature is 290 ℃, 320 ℃ and 350 ℃ _nH3, by the way, carry out apparent kinetics parameter A, E, A that linear fit obtains meeting denitration reaction _nH3and H _nH3, according to the kinetic parameter of asking for, then matching obtains kinetic parameter variation rule curve figure, is used for predicting the kinetic parameter Changing Pattern of catalyzer, thereby can provide technical support for the formulation of the SCR of power plant denitrating system operation regulation scheme.

Shown in Fig. 3 and Fig. 4, the fitted figure that Fig. 3 is the kinetic parameter before the corrugated plate catalyzer is on active service, the fitted figure that Fig. 4 is the kinetic parameter after the corrugated plate catalyzer is on active service.As can be seen from the figure, degree of fitting is all more than 0.94.

Reference table one is the kinetic parameter before and after two kinds of typical catalyst are on active service shown in table.Can find out, energy of activation before the corrugated plate catalyzer is on active service is 14918.17J/mol, pre-exponential factor is 1261.53/s, energy of activation after military service is 14955.43J/mol, pre-exponential factor is 1003.79/s, visible, little than after being on active service of the energy of activation before the corrugated plate catalyzer is on active service, but large than after being on active service of the pre-exponential factor before being on active service.The energy of activation of the NH3 balancing speed constant before the corrugated plate catalyzer is on active service is-12068.2J/mol, pre-exponential factor is 170.20m3/mol, after being on active service, the energy of activation of NH3 balancing speed constant is-16393.7J/mol, pre-exponential factor is 83.19m3/mol, and the energy of activation of the NH3 balancing speed constant before the corrugated plate catalyzer is on active service and pre-exponential factor be large than old catalyzer all; The kinetic parameter of honeycombed catalyst also meets this rule.

Table one

The measuring method of kinetic parameter Changing Pattern after SCR denitrating system catalyzer military service of the present invention, mode based on experiment and calculating coupling, catalyst chemical course of reaction by the in commission SCR denitrating system of simulated field, then calculate the kinetic parameter of catalyzer according to the related experiment data, matching obtains kinetic parameter variation rule curve figure again, be used for predicting the kinetic parameter Changing Pattern of catalyzer, thereby can provide technical support for the formulation of the SCR of power plant denitrating system operation regulation scheme.

The above embodiment has only expressed several embodiment of the present invention, and it describes comparatively concrete and detailed, but can not therefore be interpreted as the restriction to the scope of the claims of the present invention.It should be pointed out that for the person of ordinary skill of the art, without departing from the inventive concept of the premise, can also make some distortion and improvement, these all belong to protection scope of the present invention.Therefore, the protection domain of patent of the present invention should be as the criterion with claims.

Claims (6)

1. the measuring method of the rear kinetic parameter Changing Pattern of SCR denitrating system catalyzer military service, is characterized in that, comprises the steps:

Build SCR catalyst activity test experience platform, this experiment table comprises:

The trace water pump, carburetor, mixer, primary heater, add electrothermal stove, NO gas standard gas cylinder, O ₂gas standard gas cylinder, N ₂gas standard gas cylinder, NH ₃gas standard gas cylinder, reactor and flue gas analyzer; Wherein, micro-water pump, carburetor, primary heater, reactor connect by conduit; Mixer connects NO gas standard gas cylinder, O by conduit ₂gas standard gas cylinder and N ₂the gas standard gas cylinder, access respectively NO gas, O ₂gas and N ₂gas; Reactor connects NH by conduit ₃the gas standard gas cylinder, access NH ₃gas; Carburetor produces H ₂o gas, reactor is placed in and adds electrothermal stove;

The experimental implementation process is as follows:

Cut out coupon the monoblock catalyzer of being on active service from scene, coupon is placed in reactor, set the experiment parameter of each experiment, comprising: inside reactor temperature, experimental gas import volume and ammonia nitrogen ratio;

During experiment, first pass into O ₂gas and N ₂gas, start and to add electrothermal stove, with constant heating rate, inside reactor is heated to design temperature, until temperature, keep after stable passing into NO gas, after the concentration stabilize of NO, record flue gas analyzer record the NO gas concentration; Then pass into NH ₃gas is reacted in reactor, after the NO gas concentration after question response tends towards stability, record flue gas analyzer record the NO gas concentration;

Set up the Chemical Reaction Model of catalyst reactor, NO gas concentration parameter according to record, the structural parameters of catalyzer and Chemical Reaction Model are calculated the kinetic parameter of catalyzer, respectively each ammonia nitrogen than under kinetic parameter corresponding to each temperature of matching, obtain the kinetic parameter variation rule curve figure of catalyzer before and after being on active service.

2. the measuring method of kinetic parameter Changing Pattern after SCR denitrating system catalyzer military service according to claim 1, is characterized in that, in described experiment, the inside reactor temperature is respectively 290 ℃, 320 ℃, 350 ℃, 380 ℃; In experiment, gas is NO gas 300ppm, O ₂gas is 5%, H ₂o gas is 10%, and remainder is N ₂gas; The ammonia nitrogen ratio is respectively 0.5,0.8,1.1.

SCR denitrating system catalyzer according to claim 1 be on active service after the measuring method of kinetic parameter Changing Pattern, it is characterized in that, after experimental data is stablized 30 minutes, record flue gas analyzer record NO gas concentration data.

SCR denitrating system catalyzer according to claim 1 be on active service after the measuring method of kinetic parameter Changing Pattern, it is characterized in that, the catalyzer of experiment comprises: the honeycombed catalyst of the corrugated plate catalyzer of new corrugated plate catalyzer and military service 40200h, new honeycombed catalyst and military service 20000h.

5. the measuring method of kinetic parameter Changing Pattern after SCR denitrating system catalyzer military service according to claim 1, is characterized in that, every kind of catalyzer repeats twice experiment, and record data are the mean value of getting twice experiment.

6. the measuring method of kinetic parameter Changing Pattern after SCR denitrating system catalyzer military service according to claim 1, is characterized in that, the Chemical Reaction Model of described catalyzer comprises:

The governing equation of element of volume, as formula:

$R_{\mathrm{NO}}=(1-{\mathrm{\ϵ}}_B)\·A\·\mathrm{dl}=A\·u\·C_{\mathrm{NO}}^0{\mathrm{dx}}_{\mathrm{NO}}$

In formula, R _nOnO reaction rate (mol/m for per volume of catalyst ³-cat/s), ε _bfor the porosity of beds, A is catalyst inlet sectional area (m ²), the length that l is catalyzer, the superficial velocity that u is flue gas (m/s),

reactor inlet volumetric molar concentration (mol/m for NO ³), x _nOconversion ratio for NO.

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