FIELD OF THE INVENTION
The invention generally relates to measurement of conductivity of flue gas dust
from electrostatic precipitators (ESP) under lab condition. More particularly, the
invention relates to a device for measuring conductivity of flue gas dust to
enhance performance of Electrostatic precipitators.
BACKGROUND OF THE INVENTION
Electrostatic precipitation is one of the most effective ways to control air
pollution generated by industrial emissions. This technique, which has proven
highly effective in controlling air pollution, has been used for removal of
undesirable matter from a gas stream by electrostatic precipitation. Electrostatic
precipitator (hereafter referred to as ESP) is an air pollution control device
configured to electrically charge and collect particulates generated from industrial
processes such as those implemented in power plants, cement plants, pulp and
paper mills and utilities etc. The electrically charged particles are attracted
towards electrode plates, viz., discharge electrode and collection plate. ESP is
divided into a plurality of fields depending on the dust load. A field is
considered healthy as long as it is charge with sufficient voltage and current
between its discharge and collection plate. During continuous operation of an
electrostatic precipitator, the dust from collector plates & discharge electrodes
must be periodically removed for further conveying of the collected dust. The
dust removal mechanism typically consists of a mechanical rapper.
The performance of an ESP depends on various factors including the voltage
applied between its electrodes, current consumed by each field, flue gas
conductivity, flue gas composition, temperature and moisture. These parameters

have varying levels of impact on performance. Except conductivity, other
significant parameters are measured directly inside the EP. Direct measurement
of Conductivity and impact on conductivity by other chemicals, on the other
hand, are measured only in Laboratory. Special equipment are required to
perform such measurements.
In the prior art, equipment are available to make measurement of conductivity
under laboratory conditions. That may include moisture injection and
temperature controlled environment. Equipments are made to a specific voltage
levels to be applied across dust samples.
In the prior art, equipment are also available to measure the conductivity of
dust samples collected from the plants conditioned with chemicals like Ammonia
and SOx. For this, the measuring equipment is not modified accordingly. The
preconditioned samples are just used as any other samples in these equipments.
Thus, the prior art, fails to provide a measuring device for conditioning of
chemicals to be added with dust samples at controlled atmosphere including
temperature and moisture, selecting, the dosage levels of the chemical and
determine direct impact on conductivity to improve performance of the
electrostatic precipitator.

OBJECTS OF THE INVENTION
It is therefore, an object of the invention to propose a device for measuring
conductivity of flue gas dust to enhance performance of Electrostatic
precipitators, which is enabled to emulate the plant condition at laboratory to
determine the impact of chemical dosing on the flue gas dust.
Another object of this invention is to propose a device for measuring conductivity
of flue gas dust to enhance performance of Electrostatic precipitators, which is
configured to measure the amount of chemical dosing in terms of kilograms/day
required for a plant.
Yet another object of the invention is to propose a device for measuring
conductivity of flue gas dust to enhance performance of Electrostatic
precipitators, which is capable to measure the impact of chemicals dosing on
conductivity of the flue gas at various values of temperatures and moistures.
SUMMARY OF THE INVENTION
The performance of an EP is largely dependent on conductivity of flue gas dust,
for example, a higher conductivity results in poor performance of the EP. Prior
art: teaches several techniques for reducing the conductivity to required level,
and vis-a-vis improving EP performance. One such method is to add AMMONIA
gas in the flue gas. Such chemical addition is found to provide an improved
performance of the EP. However, it is not quite clear as to the physical or
chemical reason which causes the improvement in the performance.

Accordingly, the present invention provides a device for measurement of
conductivity of flue gas dust under the influence of ammonia gas. Impact of
ammonia on conductivity can be measured more accurately in respect of dosage,
temperature, moisture and treatment-time. Such measurements are not possible
in plant where the EP is operating.
The device is configured to accurately deliver such amount of ammonia into a
measuring chamber and control means are enabled to maintain the set
temperature and moisture levels.
The dosage level of ammonia is calculated based on test requirement in terms of
ml/min. The anhydrous ammonia is diluted with nitrogen gas to a specific ratio
so that the flow remains within 1 to 10 ml/min for the said ammonia dosage.
The invention will now be described in detail with reference to the accompanying
drawings.
BREIF DESCRIPTION OF ACCOMPANYING DRAWINGS
Figure 1 is a block diagram illustrating General arrangement of a conductivity
meter.
Figure 2 is a block diagram illustrating Ammonia Injection System.
Figure 3 is a flow diagram for conducting ammonia injection for the testing.

DETAIL DESCRIPTION OF THE INVENTION
The invention provides a testing device for determining conductivity of flue gas
dust including an ammonia injection means. The device enables determining and
injecting a precise level of ammonia dosage at a particular temperature and
moisture. These conditions are synonymous to plant conditions with features to
cover entire range of parameter variation for lab testing. The device allows
determining exact amount of ammonia required to meet the required
performance for a full-scale plant.
In the block diagram shown in figure 1, a measuring chamber (1) contains a flue
gas dust sample collected from a plant and kept in a container (6) to represent
plant conditions, wherein the dust is collected in a collecting electrode. A power
supply controller (2) applies around 500V across the sample (6). The chamber
(1) receives heated air at a particular temperature from air temperature control
means (3). A moisture control system (4) injects required amount of moisture
into the chamber (1). An ammonia injection system (5) developers required
amount of ammonia gas form into the chamber (1).
In the block diagram shown in figure 2, an ammonia gas container (8) is
prepared with required dilution with nitrogen (15) to meet a specified dosage
level. It is connected to a pressure gauge (9) and a Pressure Reducing Valve
(PRV) (10). The pressure is reduced to a considerable level using the PRV and
then connected to flow Meter (11) to indicate the flow during operation. A piping
means is then connected to the chamber (1) via an isolation valve (12). The
controlled injection of ammonia is achieved through this process.
The process of ammonia dosage calculation and injection is explained in figure 3.
First the required amount of ammonia and its flow rate is calculated (14). The
flow meter (11) connected is selected to have a range of 1ml/min to 10ml/min.

The dilution of ammonia with nitrogen (15) is decided based on the range of the
flow rate meter (11). The required values of temperature and moister is set (16)
using respective temperature and humidity controllers. The sample is kept (17)
in this state for about 30min and the readings are taken before moving to a next
temperature (18).
The invention thus provides a device to determine the impact on conductivity of
flue gas dust based on ammonia dosage level in various temperature range
under specified moisture level. This device generate operating conditions of the
original plant so that the tests can be conducted without any difficulties. The
output from the device can be used to measure the amount of ammonia required
to use in full-scale plant to meet the required performance.

WE CLAIM:
1. A device for measuring conductivity of flue gas dust to enhance
performance of Electrostatic precipitators, comprising a chamber (1), a
Power supply controller (2), an air temperature control means (3), a
moisture control means (4), and an ammonia injection means (5), wherein
the power supply controller (2) delivers a required voltage, wherein the
temperature control means (3) enables maintaining an air temperature
inside the chamber (1) at a set value, wherein the moisture control means
(4) maintains a moisture level in the chamber (1) at a required dew point
setting, wherein the ammonia injection means (5) delivers a measured
amount of ammonia into the chamber (1).
2. The device as claimed in claim 1, wherein the required voltage is 500v DC.
3. The device as claimed in claim 1, wherein the temperature control means
(3) is operated to vary temperature up to 300° from ambient inside the
chamber (1).
4. The device as claimed in claim 1, wherein the dew point temperature is set
between 30°C to 80°C.
5. The device as claimed in claim 1, wherein the ammonia injection means (5)
is enabled to inject the ammonia in gas form.
6. The device as claimed in claim 1 or 5, wherein the ammonia injection
means (5) inject the ammonia diluted with nitrogen gas to a required level.

7. The device as claimed in claim 5 or 6, wherein the ammonia injection
means (5) comprises a pressure-reducing valve (10), a flow meter (11) and
an isolation valve (12).
8. A process for determining ammonia dosages to be injected into the
chamber (1) of the device as claimed in claim 1, the process comprising the
steps of:
calculating (14) the amount of ammonia and its flow rate;
estimating (15) dilution of ammonia with nitrogen to correspond range
of the selected flow meter;
commencing (16) ammonia injection with temperature and moisture
setting;
allowing (17) the test sample to stabilize under said temperature and
moisture setting; and
progressing (18) the process to a next temperature setting, and record
new readings of the injection parameters.

ABSTRACT

The invention relates to a device for measuring conductivity of flue gas dust to
enhance performance of Electrostatic precipitators, comprising a chamber (1), a
Power supply controller (2), an air temperature control means (3), a moisture
control means (4), and an ammonia injection means (5), wherein the power
supply controller (2) delivers a required voltage, wherein the temperature control
means (3) enables maintaining an air temperature inside the chamber (1) at a
set value, wherein the moisture control means (4) maintains a moisture level in
the chamber (1) at a required dew point setting, wherein the ammonia injection
means (5) delivers a measured amount of ammonia into the chamber (1).