RU2337747C1 - Method for controlling regeneration of bag type filters - Google Patents

Abstract

FIELD: chemistry, technological processes.

SUBSTANCE: method for controlling regeneration of bag type filters includes supply of dust-laden gases into bag-type filter, regeneration of the bag-type filters by blowing with compressed air and after a specific period of time, the measurement of the pressure of gases before and after the module of the bag-type filters. Time interval between regenerations of the bag-type filters is established depending on the pressure difference before and after the module of the bag-type filters, thus are established maximal and minimal time intervals between impulses on the regeneration of filters, and also the minimal and maximal values of pressure difference on the module bag-type filters, and in case of the minimal and maximal preset values of pressure differences are established, accordingly, the maximal and minimal set time intervals between impulses for regeneration, and in case of intermediate value of pressure difference between its minimal and maximal preset values of the time interval between the impulses for regeneration are determined under the formula given in the application.

EFFECT: automatic regulation of time interval between regenerations of filters and actions of jets of compressed air depending on pressure difference on bag-type filter; increase in level of cleaning of gases and decrease in expenditure of compressed air at regeneration.

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Description

The invention relates to a continuous process of "dry" gas purification of electrolysis production, and in particular to a control system for the regeneration of bag filters.

Known methods for the regeneration of bag filters of the process of "dry" gas purification, including shaking the filters and purging with compressed air at predetermined specific points in time [1, p. 39-42], [2, p. 419, p. 655-656].

There is also a method of controlling the regeneration of bag filters, in which pulses of compressed gas are sequentially supplied to the purge manifolds [3].

However, the disadvantage of this method is the constancy of the parameters of the regeneration process: the duration and the interval between pulses, which leads to a decrease in the filter efficiency (degree of dust removal) as the filter becomes clogged and its filtration ability decreases.

Thus, a known method of controlling the regeneration of bag filters, in which pulses of compressed gas are sequentially supplied to the purge manifolds, which is the closest analogue of the proposed method and selected as a prototype [3]. The known method produces sequential regeneration of the channels of the bag filter, i.e. the parameters of the regeneration process — the pulse duration and the interval between pulses — are fixed.

The disadvantage of this method is that the duration of the interval between pulses is a fixed value, which leads to a decrease in the filter efficiency (degree of dust removal) as the filter becomes clogged and its filtering ability decreases.

The technical result of the invention is the regulation of the time interval between regenerations of filters and the action of jets of compressed air depending on the pressure drop across the bag filter, which, in turn, provides an increase in the level of purification of dust, in particular electrolysis gases. Moreover, by increasing the degree of purification, it is possible to reduce the consumption of compressed air for regeneration up to 2%. This technical result is achieved in that a known method for controlling the regeneration of baghouse dust filters includes the supply of dusty gases to the baghouse filter, regeneration by blowing bag filters with compressed air and after a certain period of time, measuring the gas pressure before and after the bag filter module, characterized in that the time interval between regenerations of bag filters is set depending on the pressure drop before and after the bag filter module, while the maximum and minimum the maximum time intervals between the pulses for filter regeneration, as well as the minimum and maximum pressure drops on the bag filter module, and in the case of the minimum and maximum specified pressure drops, set the maximum and minimum specified time intervals between pulses for the regeneration, and in the case of intermediate value of the differential pressure between its minimum and maximum specified values, the time interval between pulses for regeneration is determined by mule

,

,

where t _u is the time interval between pulses for filter regeneration, s; t _u.max - specified maximum value of the time interval between pulses, s; t _u.min is the specified minimum value of the time interval between pulses, s; ΔР - current pressure drop of gases on the bag filter module, kPa; ΔР _max - set value of the maximum pressure drop, kPa; ΔP _min - set value of the minimum pressure drop, kPa.

It is known that the cleaning efficiency is inversely proportional to the filtering ability of the filter, determined by the degree of clogging of the bag filter. To increase the degree of gas purification, in this case, in the case of bag filters with a cycle for regeneration by shaking and supplying compressed air, it is proposed to set the time interval between regenerations depending on the degree of clogging of the filter, which, in turn, is carried out by the pressure drop before and after the bag filter module . In the proposed method, a pressure measurement before and after the bag filter module and setting the time interval between the pulses for filter regeneration depending on these measured pressure drops are introduced into the bag filter regeneration control algorithm. In this case, the values of the minimum and maximum pressure drops and, accordingly, the maximum and minimum time between pulses for regeneration are set, and in the intervals between these predetermined time intervals, the time between pulses is set inversely to the pressure drop.

Figure 1 shows a graph of the regulation of the interval between pulses depending on the pressure drop across the bag filter.

The maximum, minimum interval between pulses, as well as the minimum and maximum values of the differential pressure are set in accordance with the values recommended by suppliers of gas cleaning equipment. At the current pressure drop less than the minimum set value of the pressure drop 1, the interval between pulses is equal to the maximum specified interval between pulses. When the current pressure drop is greater than the maximum specified value of the pressure drop 3, the interval between pulses is equal to the minimum specified interval between pulses. When the current pressure drop is greater than the minimum set value of the pressure drop and less than the maximum set value of the pressure drop 2, then the interval between pulses is calculated by the formula.

Since in order to maintain the required level of purification of electrolysis gases, it is necessary to have a certain dust layer on bag filters [1], the application of this method will make it possible to maintain this layer. With a greater pressure drop - there is a lot of dust - regeneration will be carried out more often, dust will be lost. With a smaller difference - there is little dust - regeneration will be made less frequently, dust will be deposited on the filtering partition.

The proposed method is implemented using the device shown in figure 2. The device includes an automatic control object 4, a differential pressure sensor 5, an element for comparing the output value of the differential pressure on the module of the bag filters of the object with the specified minimum and maximum values 6, a unit for calculating the time interval between pulses for the regeneration of bag filters 7, a timer unit for the duration between pulses 8, pulse duration timer unit 9, control action, preset maximum and minimum values of UV.

The device operates as follows. The sensor 5 measures the pressure drop on the bag filter module, which is the object of automatic regulation 4. The sensor readings are compared in the comparison element 6 with the control action Uv - the specified maximum and minimum pressure drops. Further, in the unit for calculating the time interval between pulses for the regeneration of bag filters 7, the duration of the pause between pulses is calculated. Then, this time interval is processed in the duration timer unit between pulses 8, then the air pulse itself is processed, the duration of which is controlled by the pulse duration timer unit 9. Blocks 6, 7, 8, 9 operate using an algorithm for calculating the duration between pulses depending on differential pressure on the module of the bag filter shown in Fig.3. The algorithm works as follows.

First, switching from one bag filter module to another is performed, checking the number of the current module. And if all the modules are processed, then processing starts first, from the first module, and therefore the number of the current module is equal to 10. Then, the operating mode of module 11 is checked. If the current mode is an automatic control mode, then the data is read. Otherwise, the work on the algorithm ends. After reading the data, the differential pressure across the bag filter module is compared with the minimum specified differential pressure 12. If the current differential pressure is less than the minimum specified, then the duration between pulses will be equal to the maximum specified duration.

Otherwise, it compares whether the current pressure drop across the bag filter is less than the maximum specified pressure drop 13. If the condition is not fulfilled, the duration between pulses will be equal to the minimum specified duration. If the current pressure drop across the bag filter is less than the maximum preset pressure drop 14, then check and check that the denominator is not equal to zero. The duration between pulses is calculated by the formula. After determining the duration between pulses, the pulse duration is determined equal to half a second 15. We determine the duration of the regeneration cycle equal to the sum of the pulse duration and the duration between pulses multiplied by the number of channels. The obtained time intervals - the duration between pulses, the pulse duration, the duration of the regeneration cycle - are recorded in the memory.

Figures 4 and 5 show an algorithm for processing timers of pulse durations, pauses between pulses. The algorithm works as follows.

The determination of the last triggered regeneration channel is carried out and it is checked whether the last triggered channel and the current 16 and 18 are identical. This implies that this information about the channels is stored in arrays. It is converted to an array each time the algorithm is read - the bit "1" is raised by the channel number opposite the corresponding channel in the array of the last triggered channel. Bit "1" opposite the corresponding channel in the array of the current channel is raised only when the timer sets the specified interval of time between pulses. Therefore, when these arrays are identical, the channel of the bag filter is regenerated. Further, if the arrays are not identical, the duration timer is processed between pulses 17. The condition is checked whether all the channels have worked. If everything worked out, then the interval between the last and first pulses is counted. When the interval is counted, the duration timer between pulses is reset, the last activated channel and the current channel are set. If not all channels have worked, then the interval between pulses is counted. When the interval is counted, the channel counter is increased, the last triggered channel and the current channel are set. Next, whether block 17 was performed or the transition was from block 16, the last activated regeneration channel 18 is determined. This is done so that during the same reading of the algorithm, as soon as the interval timer between pulses has worked, the bag filter channel is regenerated. If regeneration 19 is performed, then the pulse duration timer is processed, after which time the current channel is reset and the pulse duration timer is reset.

Example. When implementing this method on the bag filter of a dry gas treatment plant of the Bogoslovsky aluminum plant, the following parameters were found, which were found experimentally, to control the regeneration of bag dust

filters depending on the pressure drop: t _u.max = 300 s; t _u.min = 60 s; ΔP _max = 1200 kPa; ΔP _min = 900 kPa. The pressure drop across the bag filter, ΔP, was, rounded, equal to 1100 kPa. Due to the fact that the current pressure drop across the bag filter ΔP falls within the pressure drop range that the automation should support, the calculation of the time interval between pulses for filter regeneration, t _u , will be performed according to the formula:

.

.

The use of such a method for controlling the regeneration of bag filters allows you to adjust the time interval between the regeneration of filters and the action of compressed air jets depending on the pressure drop across the bag filter, which, in turn, provides an increase in the level of purification of dust, in particular electrolysis gases. At the same time, by increasing the degree of purification, it is possible to reduce the consumption of compressed air for regeneration up to 2%.

BIBLIOGRAPHY

1. Purification of technological and fugitive emissions from dust in the steel industry / Tolochko AI, Filipiev OV, Slavin VI, Guryev B.C .; M .: Metallurgy, 1986. 208 p.

2. Foreign and domestic equipment for gas purification: Reference publication / MGLadygichev, G.Ya. Bergner. - M.: Heat engineer, 2004.669 s.

3. SU 1215213, 1994.06.30, B01D 46/02

4. Theses of the XI scientific-practical conference "Aluminum of the Urals - 2006", pp. 157-158

Claims (1)

A method for controlling the regeneration of baghouse dust filters, including the supply of dusty gases to the baghouse filter, the regeneration of baghouse filters by blowing with compressed air and after a certain period of time, measuring the gas pressure before and after the baghouse filter module, characterized in that the time interval between the baghouse filter regenerations is set to depending on the pressure drop before and after the bag filter module, while setting the maximum and minimum time intervals between pulses for regeneration filters, as well as the minimum and maximum values of the pressure drop across the bag filter module, and in the case of the minimum and maximum specified values of the pressure drops, respectively, the maximum and minimum specified time intervals between regeneration pulses are set, and in the case of an intermediate pressure difference between it minimum and maximum set values, the time interval between pulses for regeneration is determined by the formula

, where t _u is the time interval between pulses for filter regeneration, s; t _u.max - specified maximum value of the time interval between pulses, s; t _u.min is the specified minimum value of the time interval between pulses, s; ΔР - current pressure drop of gases on the bag filter module, kPa; ΔP _max - set value of the maximum pressure drop, kPa; ΔP _min - set value of the minimum pressure drop, kPa.

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