JPS61141934A - Method for determination of regeneration period of catalyst - Google Patents

Abstract

PURPOSE:To determine a proper regeneration period by accurately detecting the lowering in catalytic activity, by judging not only the point of time when the catalytic reaction rate of a catalyst packed bed is reduced to a set value or less and the pressure loss of said catalyst packed bed reaches a set value or more but also the regeneration period. CONSTITUTION:Densitometers 2, 3 for measuring the concn. of NOx in exhaust gas and a differential pressure gauge 4 are provided to the upstream and downstream sides of a catalyst packed bed 1 to calculate the pressure loss P and catalytic reaction rate X of the catalyst packed bed 1. Then, the amount of exhaust gas is corrected to a usual average flow amount with respect to the pressure loss P of an experimental value and the ratio of NOx-concn. and the amount of the exhaust gas to the catalytic reaction rate X is corrected to a usual average value and denitration reaction temp. to usual average temp. to set the index of the lowering in catalytic activity. By this method, the lowering in the activity of the catalyst is certainly detected and the regeneration period thereof can be made adequate.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for determining catalyst regeneration timing in a gas-solid catalytic reaction mechanism in which a gas containing dust is passed through a solid catalyst packed bed.

[Conventional technology]

A heterogeneous catalytic reaction in which a gas containing dust is passed through a solid catalyst packed bed differs from a homogeneous catalytic reaction in that the reaction occurs at the interface between the solid catalyst layer and the gaseous reactant phase. That is, since the reaction proceeds two-dimensionally on the catalyst surface, the accumulation of dust in the gas on the catalyst surface causes a decrease in the catalyst activity.

Therefore, the apparent catalytic activity decreases over time even if the reaction conditions such as the total lit ni of gas, the amount of reactants, the reaction temperature, and the reaction time are the same. Catalyst regeneration is performed by removing the catalyst and returning it from the top of the packed bed to remove accumulated dust and restore catalyst activity.

However, due to fluctuations in various reaction conditions, the degree of dust accumulation and the resulting reduction in catalyst reaction rate varies, and it is necessary to perform regeneration by catalyst transfer irregularly depending on the situation. The problem was how to determine the timing.

In a chemical reaction system, the first objective factor required is the reaction rate, so even in the above-mentioned reaction system, when it is found that the catalytic reaction rate may be lower than the required minimum reaction rate, the catalyst It is reasonable to carry out regeneration and try to recover the catalyst activity. However, in industrial-scale processes that are connected to other processes, the total flow of gas 'ill, reactant j-1
Since the reaction conditions such as reaction temperature and reaction time vary considerably, the actual catalytic reaction rate determined from the amount of reactants before and after the catalyst packed bed fluctuates greatly and can be used as an indicator of a decline in catalyst 1III1.・There were cases where it was not appropriate to make an objective judgment.Therefore, it was a good idea to correct the actual AI's reaction rate against all possible fluctuations in the reaction conditions.

However, even if the catalytic reaction rate is corrected, Fig. 5(a)
As shown in point 5, even though Das[• has not accumulated much in the reactor and the true catalytic reaction Il has not decreased significantly, the apparent −1−temporary catalytic reaction If the rate drops abnormally, it may be determined that it is time to move the catalyst. Conversely, as shown at point 6 in Figure 5(b), a large amount of dust was deposited in the reactor, and even though the true catalytic reaction rate was considerably reduced, no correction was made. There is a possibility that the catalytic reaction rate appears to temporarily increase due to fluctuation factors, so that it may not be determined that it is time to move the catalyst.

In other words, I'i! l! The catalyst reaction rate is subject to many fluctuations based on many factors, and when catalyst regeneration is performed using only the catalyst reaction rate as an index, there are cases where it is not always appropriate or there are cases where it is difficult to make a decision.

[Problem that the invention seeks to solve]

Therefore, the present invention aims to solve the problem of Ill.
! l! By using an index (JI) indicating the decrease in catalytic activity due to the catalytic reaction rate, which is different from the reaction rate, it is possible to obtain more accurate information that was inaccurate based on the catalytic reaction rate alone. The objective is to reliably and accurately detect low levels of catalyst activity due to dust accumulation and to determine the appropriate timing for catalyst regeneration.

[Means for solving problems]

As shown in Figure 2, accumulated dust in the catalyst packed bed
The increasing pressure loss ΔP in the packed bed was taken as an index that changes as +W increases. As shown in Fig. 1, ΔPs is set as a set value for the pressure loss ΔP, and Xs is set as a set value for the decreasing catalytic reaction rate X. By using this as a determining condition for catalyst movement, it is possible to achieve a reliable and efficient determination of the timing of efficient recovery of catalyst activity according to the degree of tast accumulation and the degree of decrease in catalyst reaction rate due to tast accumulation. I can do it. Note that the catalytic reaction rate X and the packed bed pressure loss ΔP are obtained by adding corrections such as the total flow rate of gas, the amount of reactants, the reaction temperature, and the reaction time to the actual Wlll value.

As shown in FIG. 3, a concentration meter 2.3 for measuring the concentration of reactants in the gas and a differential pressure gauge 4 are provided before and after the catalyst packed bed 1 for the gas-solid catalytic reaction, and the pressure of the catalyst packed bed 1 is provided. Loss ΔP
and the catalytic reaction rate X. Then, corrections are made to the actual measured values of pressure drop ΔP and catalytic reaction rate It is used as an indicator of the deposition status and the resulting decrease in catalyst activity.

Then, as shown in Figure 1, set the pressure loss ΔP and the catalytic reaction rate X (+fiΔPs, The catalytic reaction rate X is as follows (1), (
2) When the equations are satisfied at the same time, it is determined that it is time to regenerate the catalyst.

ΔP≧ΔPs ... (1) X≦Xs
...(2) In addition, Fig. 1 (a)
First, the condition of equation (2) is applied to 41', and then equation (1)
(b) shows the case where the condition of
) is shown, and then the condition of equation (2) is satisfied, and (C) shows the case where the conditions of equations (1) and (2) are satisfied almost at the same time.

〔Example〕

Using the process shown in FIG.
When performing exhaust gas denitrification treatment to reduce and remove Ox, a concentration meter 2.3 and a differential pressure gauge 4 are installed before and after the catalyst packed bed to measure the NOx concentration in the exhaust gas, and the pressure loss ΔP of the catalyst packed bed 1 is measured. and the catalytic reaction IXX were determined. Then, the υ1 gas amount is corrected to the normal average flow rate (300,000 Nm'/hr) for the actually measured pressure loss ΔP, and the ratio of NOx 9 degrees and exhaust gas amount to the catalytic reaction rate X is adjusted to the normal average flow rate. Value (4p
p m/10'Nm' h r-1), the denitrification reaction temperature was corrected to the normal average temperature (230'), and the pressure drop ΔP and catalytic reaction rate This was used as an indicator of decline.

Then, as shown in Fig. 4, the set values ΔP s and X s of the pressure loss ΔP and the catalytic reaction rate
0), 82 (%), and 1(((decreased pressure drop ΔP and increased catalytic reaction rate
The time when the following two equations were simultaneously satisfied was determined as the catalyst transfer time.

ΔP≧25...(3)X≦82
(4) As a result, it is now possible to determine the timing of catalyst regeneration without error.

〔Effect of the invention〕

According to the present invention, since a decrease in the activity of the catalyst is reliably detected, it is possible to appropriately time the regeneration.

[Brief explanation of the drawing]

Fig. 1 is a graph showing an example of catalyst transfer according to an embodiment of the present invention, Fig. 2 is a graph showing changes in dust accumulation amount, pressure loss, and catalytic reaction rate in the catalyst layer, and Fig. 3 is a graph showing an example of the application of the present invention. Figure 4 is a graph showing the general relationship between the amount of dust accumulated in the catalyst layer, pressure loss, and catalytic reaction rate. Figure 5 is a block diagram showing the configuration of the catalyst packed bed, reactant concentration meter, and differential pressure gauge. FIG. 2 is an explanatory diagram illustrating the influence of variation in reaction rate. W...Amount of dust accumulated in the catalyst packed bed, ΔP...
Pressure loss in catalyst packed bed, X... Catalyst reaction rate, M
v...catalyst movement period, ΔPs...set value of ΔP, X
s...Setting value of X, 1...Catalyst packed bed, 2.3...
・Concentration meter, 4...Differential pressure gauge.

Claims (1)

[Claims] 1 In a heterogeneous catalytic reaction in which gas containing dust is passed through a catalyst packed bed, the catalyst regeneration period is defined as the time when the catalyst reaction rate of the catalyst packed bed becomes less than the set value and the pressure loss of the catalyst packed bed exceeds the set value. 1. A method for determining catalyst regeneration timing in a gas-solid catalyst packed bed.