A case has been made for use of Eko MK 4×160 precipitating element, whose merit is that it ensures

deviations of dimensions from rectilinearity and planarity of not more than 3 mm × 18 m in EGA, EGBM,

EGB, and EGAV types of apparatuses as well as in updated versions of DGPN, DGP, PGD, UG, and EG

types of electrostatic precipitators (electric filters). Use of Eko MK 4×160 precipitating element will help

meet current requirements of dust ejections from electrostatic precipitators.

In 1965–1966, precipitating electrodes consisting of C-shaped (crescent-shaped) elements 175 and 350 mm in width

were developed in partnership with the Semibratovo Branch of the State Research Institute of Industrial and Sanitary Gas

Cleaning (SF NIIOGAZ).

Experience of use of UG type of electrostatic precipitators (electric filters) having precipitating electrodes whose

elements were 350 mm wide showed that they have greater advantage than electrostatic precipitators fitted with old type of

precipitating electrodes [1].

Investigations of electrical fields of an electrostatic precipitator [2] as well as of dust entrainment in the precipita-

tion process and electrode shaking [3] showed that the precipitating electrodes of the UG type of electrostatic precipitators

have considerable deficiencies stemming basically from imperfection of the shape (profile) of the precipitating elements.

The efficiency of a precipitating electrode having an element 350 mm in width was investigated by comparing the

relative rates of accumulation of dust on each of the seven typical sections of the electrode (Fig. 1). The relative rate of dust

accumulation was defined as the ratio of the mass of dust accumulated on each of the referred seven sections to the mass of

dust accumulated on section 2 over the same period. The data from six tests were averaged. The results of these investiga-

tions are cited in Table 1.

As can be seen from the cited data, the lowest rate of dust accumulation was noticed on sections 4 and 6 because the

electrical field on these sections is screened to a considerable extent by projecting edges. Also, the rate of dust accumulation

on sections 1, 3, and 7 is lower than on section 5.

One of the methods of enhancing the efficiency of utilization of the precipitating electrode surface is increasing the

length of sections 2 and 5 by reducing the length of the other sections. The experience of use of electrostatic precipitators

with such precipitating electrodes has shown that their deficiencies arise essentially from the imperfect shape (profile) of the

precipitating elements.

The detected deficiencies consist in the following:

1) relatively small curvature of the projecting flexions of the elements, which led to a diminution of puncture (break-

down) voltage in the electrostatic precipitator;

2) the surface areas of the projecting sections are set too high (roughly twofold), so the dust precipitated on them

spontaneously fell apart and dispersed;

Chemical and Petroleum Engineering, Vol. 46, Nos. 3–4, 2010

IMPROVING DESIGNS OF PRECIPITATING

ELECTRODES FOR UG AND EGA TYPES

OF ELECTROSTATIC PRECIPITATORS

Yu. I. Sanaev

Kondor-Eko Company, Semibratovo, Yaroslavl Region, Russia. Translated from Khimicheskoe i Neftegazovoe

Mashinostroenie, Vol. 46, No. 3, pp. 47–48, March, 2010.

0009-2355/10/0304-0187 ©2010 Springer Science+Business Media, Inc. 187

3) the surface of the precipitating elements was used inefficiently because the dust was hardly captured in the cavi-

ties of the precipitating element;

4) the dimension of the profile in the transverse section is set too high (45 mm); and

5) the layer of dust precipitated on the projecting sections of the elements of this profile is subjected to erosion, espe-

cially in the starting area of the electrostatic precipitator (filter).

In the process of further improvement of the UG type of electrostatic precipitators, the thickness of the steel band used

for making the precipitating elements was reduced from 1.4 to 1.2 mm, which allowed substantial reduction of the weight of

the precipitating elements. But, because of the peculiarities of design of the mill and complexity of its adjustment, the precip-

itating elements made of the band with the thickness of 1.2 mm (crescent-shaped and nonplanar) suffered increased deforma-

tions. The fixing plates intended for centering (aligning) the elements in the plane of the precipitating electrode ceased very

fast to function effectively because of wear and widening of the holes in the elements. The failure of the fixing plates occurred

due to crescent- and propeller-like shape of the precipitating elements arising in the process of their rolling. Also, increased

deformations may occur on account of prolonged transportation and improper storing of the precipitating elements.

As a result of the investigations, the efficiency of the UG type of electrostatic precipitators was raised to some extent by

optimizing power supply and electrode shaking conditions. The investigations showed that it is impossible to increase the degree

of gas cleaning further by UG type of electrostatic precipitators due to imperfection of the shape (profile) of the precipitating ele-

ments because its potentialities were almost fully exhausted, regardless of the technology of manufacture of the elements.

In January 1980, the engineering (detail) design for EGA type of electrostatic precipitators coordinated with

Czechoslovakia was approved. During the collaboration with Czechoslovakia, the SChS-640 (Soviet–Czech) precipitating

element with a new profile (shape) shorn of the above-noted deficiencies was developed. The crescent-shapedness and non-

planarity, which arose due to inadequate adjustment of the rolling mill or to improper transportation, unloading, and storing

of the precipitating elements, were removed without special efforts by adjustment (truing) in the electrode assembly process.

Whereas in EGA type electrostatic precipitators adjustment of deformations of the elements in the installation

process allows elimination of crescent-shapedness and nonplanarity in a major way, this is not possible in UG type of elec-

trostatic precipitators.

The tendency for such deformations of the elements as properller-shapedness and crescent-shapedness in UG type of

electrostatic precipitators persists and manifests itself particularly pronouncedly in the terminal elements, which are not fixed

from the outside. For the precipitating elements deformed due to adjustment, strong torsional vibrations arise during their shak-

ing, which cause accelerated wear of the fixing plates and ultimately misalignment of the electrode system. Practically a single

deformed precipitating element in each field of the electrostatic precipitator is enough for a sharp diminution of the degree of

gas cleaning by the electrostatic precipitator. For eliminating the defects of the precipitating elements of UG type of electrostatic

precipitators, there remains only the possibility of installation of clamps that fix the position of the element.

But when clamps are used, projections are formed on the precipitating elements, which distorts the electrical field,

causing diminution of the puncture (breakdown) voltage of the eletrostatic precipitator.

188

Fig. 1. Schematic diagram of sections of precipitating element: 1–7) number of sections.

Number of electrode sections 1 2 3 4 5 6 7

Relative rate of dust accumulation on a sectionof the element at the air flow rate of 1 m/sec

0.43 1.00 0.35 0.16 0.69 0.055 0.30

TABLE 1

Only by using automatic profiling lines could the problems associated with nonplanarity and crescent-shapedness

be solved for EGA-type electrostatic precipitators fundamentally.

In UG type of electrostatic precipitators where the precipitating elements are installed without a “hook” and the clamps

are kept the same, the puncture (breakdown) voltage will obviously be reduced, which will cause diminution of the degree of

gas cleaning to the level corresponding to the level before updating of the mill for the manufacture of precipitating electrodes

for UG type of electrostatic precipitators.

The effect of misalignment of the precipitating elements on the degree of gas cleaning is illustrated in Table 2.

As evident from the obtained results, reduction in interelectrode distance even at one point of each field of the elec-

trostatic precipitator by 10 mm will lead to a twofold increase in dust slippage and a misalignment of 20 mm, which is quite

possible if there is crescent-shapedness, to a fourfold increase in dust slippage.

For elimination of the referred deficiencies, Kondor-Eko built a specially designed rolling mill – an LA-65 automatic

cold profiling line, to manufacture Eko MK 4×160 type of precipitating elements that can be used in place of the SChS-640

elements in EGA. EGBM, EGB, and EGAB types of apparatuses as well as in updated DGPN, DGP, PGD, US, and EG types

of electrostatic precipitators.

The advantage of Eko MK 4×160 type of precipitating element is that it ensures a deviation of dimensions from the

rectilinearity and planarity of not more than 3 mm × 18 m, which will help:

1) improve the quality of assembly and save time for installing precipitating electrodes;

2) center (align) precipitating electrodes in the range ±3 mm, which will make it possible to get the most optimum

conditions of power supply to the electrostatic precipitator and, consequently, the maximum degree of gas cleaning by elec-

trostatic precipitators within the set overall dimensions;

3) reduce low-frequency vibrations arising from impact loads, increase dynamic acceleration, and, finally, improve

shaking-off of dust from the electrodes, and reduce secondary entrainment; and

4) develop an electrostatic precipitator with an electrode system up to 18 m in height and, consequently, solve the

problem of constraints faced in updating obsolescent and creating new gas cleaning plants.

Use of EGAB type of electrostatic precipitators fitted with Eko MK 4×160 type of precipitating elements helped

meet the requirements placed on dust ejections from electrostatic precipitators at a level of up to 50 mg/m3, which was not

possible where UG type of electrostatic precipitators were used.

REFERENCES

1. M. I. Birger, A. Yu. Valdberg, and B. I. Myagkov, A Handbook on Dust and Ash Catching [in Russian], Energoat-

omizdat, Moscow (1983).

2. I. K. Reshidov, “Experimental studies of electrical fields in the case of reverse corona,” Author’s Abstr. of Candidate’s

Dissertation [in Russian], Moscow (1970).

3. L. V. Chekalov (ed.), Ecological Engineering. Protection of Atmospheric Air from Dust Emissions [in Russian], Rus,

Yaroslavl (2004).

Misalignment, mmDistance between

electrodes, mPuncture voltage, kV

Relative reduction indrift rate, %

Degree of gas cleaning,%

Slippage of dust, %

0 0.15 45 0 99 1

10 0.14 42 15 98 2

20 0.13 39 33 96 4

30 0.12 36 56 89 11

189

TABLE 2