RU2282481C1 - Method of control of filter - Google Patents

Abstract

FIELD: control of filters; petrochemical industry; public facilities where cleaning of water is required.

SUBSTANCE: proposed method includes mounting filter and Venturi nozzle, measurement of pressure differential ΔP_V.n.on Venturi nozzle, measurement of pressure differential ΔP on filter, determination of ratio K= ΔP_V.n./ΔP and comparison of this ratio with permissible magnitude K_perm.=ΔP_V.n.0/ΔP₀ where ΔP_V.n. is pressure differential measured on Venturi nozzle; ΔP is pressure differential measured on filter; ΔP₀ is pressure differential on filter at maximum permissible contamination at calibrated flow rate of liquid V₀; ΔP_V.n.0 is pressure differential on Venturi nozzle at calibrated flow rate of liquid V₀; filter is disconnected for flushing when K=K_perm. For facilitated operation, it is good practice to have K=1. Filter is disconnected for flushing when ΔP_V.n.=ΔP.

EFFECT: enhanced reliability, reduced expenses for flushing; increased service life of filter due to reliable determination of degree of contamination.

2 cl, 1 dwg

Description

The invention relates to the field of filter management and can be used in the petrochemical industry, as well as in other industries that use liquid (water) purification from pollution, for example, in water treatment systems of housing and communal services.

A known filter control method in which the filter operating time is the sum of the filtering time and the flushing (regeneration) time, which consists in measuring the pressure drop across the filter and when it reaches the acceptable pressure drop, turn it off [A.A. Gromoglasov, A.S. Kopylov, A.P. Pilshchikov. Water treatment: processes and devices. M., Energoatomizdat, 1990, chap. 26.1, p. 243].

The disadvantage of this method is the narrow scope, the method is suitable only for the mode of operation of the filter at a constant flow rate and is unsuitable for other modes: in a mode with a constant pressure drop across the filter and in a mode with a variable pressure drop and a variable flow rate.

Closest to the claimed object is a filter control method in which, for specific filtering conditions, the duration of the filtering time is determined empirically, upon reaching which the filter is turned off for washing. As a rule, taking into account possible deviations of the filter operating conditions, the base duration of the filtering time is taken underestimated [N.I. Gelperin. Basic processes and apparatuses of chemical technology. - M., Chemistry, 1981, chapter VD, p. 263].

This method can be used with all three of the above filter operation modes, but has the following disadvantages:

- the need for experimental determination of the new value of the filtering time when changing the filtering mode or the degree of contamination of the fluid entering the inlet;

- the filter’s ability to operate until the maximum pressure drop is reached due to the underestimated baseline filtering time

The invention is aimed at increasing the filter service life and reducing the cost of washing by more reliably determining the degree of contamination and the time to turn off the filter for washing while increasing the reliability and efficiency of the method by providing filter control depending on the filter operating conditions and operating conditions.

This is achieved by the fact that in the filter control method, namely, that the pressure drop across the filter is measured and when the acceptable pressure drop is reached, it is turned off for washing, a Venturi nozzle is installed in series with the filter, on which the pressure drop is measured, the ratio K = ΔP _{sv is} determined /? P, it is compared with a permissible value? P = K _{additional its} /? P _o, where

ΔР _St. - the measured pressure drop at the venturi nozzle;

ΔР - measured pressure drop across the filter;

ΔР _о - pressure drop across the filter at the maximum allowable contamination and calibration fluid flow rate V _o ;

ΔР _sv is the pressure drop across the venturi nozzle at calibration fluid flow rate V _o ,

and turn off the filter for washing when equality K = K _add .

For ease of operation, it is advisable to provide K _add = 1, while the filter is turned off for washing when the equality of the pressure drops ΔР _sv = ΔР is reached.

The drawing shows a schematic diagram of a filter control installation, explaining the proposed method.

The installation consists of a filter 1 and a Venturi nozzle 2 arranged in series. To measure the differential pressure ΔР on the filter, a sensor (differential pressure gauge) 3 is used; to measure the differential pressure ΔР _s between the inlet of the Venturi nozzle and the minimum nozzle section, the differential pressure sensor 4.

In the turbulent flow regime, the pressure drop ΔР on the filter and the pressure drop on the Venturi nozzle ΔР _{St. are} directly proportional to the square of the flow rate. With a fixed degree of filter contamination, the ratio of the pressure drops across the Venturi nozzle and the filter K = ΔР _sv / ΔР is a constant value that does not depend on the flow rate flowing through the filter and the Venturi nozzle.

The maximum allowable pressure drop across the filter ΔP _о at a given flow rate V _o and the pressure drop across the Venturi nozzle ΔP _sv at the same flow rate are the calibration data of the filter and nozzle, known in advance. According to these data, the permissible deviation of the pressure drops K _add = ΔР _sv / ΔР _{о is} determined.

In the process of filtering, the values ΔР and ΔР _{St. are} monitored, their ratio K is determined and compared with K _add. When K> K, the _additional filter has a working resource. When the equality K = K is reached, the _additional filter is turned off for washing.

The most convenient in operation is to turn off the filter for washing at K _extra = 1, i.e. in the case of ΔP = ΔP _St.

When controlling filters installed in parallel, a Venturi nozzle is connected in series to each filter. When reaching at some of the filters equality K = _dop this filter is switched to washing, after which is connected to the installation. Moreover, if the filters and venturi nozzles in the installation have the same parameters, then K _add for all filters is the same. If these parameters differ, then each filter has its own value To _add .

With the proposed method for controlling the operation of the filter, the latter is turned off when the maximum permissible filter pollution is reached, regardless of the operating mode (with a constant pressure drop and a variable flow rate, with a constant flow rate and a variable pressure drop, with a variable pressure drop and flow rate), regardless of the change in the degree of contamination coming in fluid inlet and from the transition to cleaning the liquid with a different density.

Thus, the use of the proposed method in comparison with the prototype will increase the service life of the filter and reduce the cost of washing it due to a more reliable determination of the degree of contamination and the time to turn off the filter for washing. In addition, the proposed method does not depend on a change in the operating mode of the filter, changes in the parameters of the liquid entering the inlet and the degree of its contamination, which makes it more efficient and reliable.

Claims (2)

1. The method of controlling the filter, namely, that the pressure drop ΔP on the filter is measured and when the acceptable pressure drop is reached, it is turned off for washing, characterized in that a Venturi nozzle is installed in series with the filter, on which the pressure drop ΔP _s is measured, the ratio K is determined = ΔР _St. / ΔР, compare it with an acceptable value To _add = ΔР _sv / ΔР _о , where ΔР _St. - the measured pressure drop at the venturi nozzle; ΔР - measured pressure drop across the filter; ΔР _о - pressure drop across the filter at the maximum allowable contamination and calibration fluid flow rate V _o ; ΔР _sv is the pressure drop across the venturi nozzle at calibration fluid flow rate V _o , and turn off the filter for washing when equality K = K _add . 2. The method according to claim 1, characterized in that they provide K _extra = 1, while the filter is turned off for washing when equal pressure differences ΔР _St. = ΔР are reached.