FIELD OF INVENTION
The invention relates to a system which will monitor the abnormal ash levels in the electrostatic precipitator (ESP) hoppers. More importantly, the invention is to make an interlock between ESP and Boiler. By acting as a pre-warning system it can prevent overloading of Hoppers by alerting the boiler operator on monitoring Ash level high in hoppers so that he can take preventive works like isolating the Pass and even tripping the boiler in severe cases.
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 designed to electrically charge and collect particulates generated from industrial processes such as those occurring 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. 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. A mechanical rapper is used to dislodge dust from the ESP electrodes by periodic rapping process. Particulates dislodged from the plates fall into collection hoppers at the bottom of the precipitator.
In ESP almost 90% of the dust is collected in hoppers of the first three fields in each passes. So it is to be evacuated regularly once high ash level alarm is enabled. But it is found that even the hoppers are full, the ESP is continuously running and the hoppers are used as if it is storage and are evacuated at operators convenient time.

In recent cases, boiler is being kept in continuous operation without properly evacuating ash from hoppers resulting in damages to ESP internals. In some cases there is collapse of the whole ESP system due to over-weight created by accumulation of Ash in the Hopper.
This has resulted in unnecessary cost in maintenance and repair of the ESP and
the damages caused by this condition has led to reduction in power generation
as well as plant availability & revenue.
So to avoid such condition it is proposed to have a system which will
warn/advice the boiler operator for necessary and immediate action due to High
Ash Level in the hopper and during under voltage condition caused by Ash build
up.
In the prior arts like IN587KOL2014A- where the invention relates to an advanced system for continuous and reliable monitoring of Ash level and Hopper Heater status of Electrostatic Precipitator but is not about the safety and overloading of the Hoppers.
The prior art for example, CN 202734909 U disclose ways to detect ash accumulation in suitable storage area or Hopper. However, it does not have any provision or design to alert the operator to evacuate the hopper in different conditions. The prior art patents for example WO 2007051239 Α1 & ΕΡ 0052435 Α1 discloses an integrated management system and efficiency enhancement method for ESP. But they are not disclosing ash level status are monitored and used in main plant Distributed Control System (DCS). It does not have any provision or design to alert the operator to evacuate the hopper in different conditions. CN203519144U, the utility model relates to a manual ash level detector. But it is not disclosing its usage in reducing the boiler load and closing the inlet valve for evacuating the affected Passes in different conditions.

The prior art CN107166361A deals with reducing the boiler load of Thermal power unit during the induced draft fan blower failure in the automatic control system and tripping the boiler in worst case but it doesn’t say anything about tripping of boiler due to ESP hopper level high. Similarly, the Trip control system patent CN202209673U for circulating fluidized bed boiler, talks of boiler tripping and load reduction based on ID fan tripping internal boiler pressure etc. but not because of high level in ESP hoppers. In patent CN103216811A all relevant boiler trips are embedded in PID loop but boiler trip due to ESP has not been envisaged.
OBJECTS OF THE INVENTION
An object of the invention is to overcome the aforementioned and other drawbacks existing in prior art systems and methods.
It is therefore an object of the invention to develop a system, which will continuously monitor ash levels in Hoppers and alert the operator when the two third of the first three field hoppers are at high level to evacuate the hopper.
Another object of the invention is to propose an improved system which will alert the boiler operator when two third of the three fields hopper are under voltage due to high level of Ash in the hoppers.
Yet another object of the invention is to propose an improved system which will alert the boiler operator if the Ash level high coming in two third of the three field hoppers and is available in ONE or TWO passes to reduce the load accordingly and isolate the effected ESP pass so as to prevent it from overloading.
Further object of the invention is to propose an improved system which will alert the boiler operator if the Ash level high coming in two third of the three field

hoppers and is available in more than TWO passes then trip the boiler so as to prevent it catastrophic damages to internals of ESP which may go beyond repair and in some cases to prevent it from collapse of ESP pass from overloading as well.
Overall the improved system is proposed to prevent ESP from unwanted delay in completing the project on time due to the above said damages.
These and other objects and advantages of the present invention will be apparent to those skilled in the art after a consideration of the following detailed description taken in conjunction with the accompanying drawings in which a preferred form of the present invention is illustrated.
SUMMARY OF THE INVENTION:
The present Application discloses a system for monitoring abnormal ash levels in Electrostatic Precipitators (ESP) Hoppers divided into number of passes with each of the number of passes having number of ESP Hopper fields. In an aspect, the system includes multiple sensors (9) configured to measure hopper ash level in the plurality of the hoppers in each pass. In another aspect, the system implements a control unit (2) further having input buffer cards (6) configured to receive signals from the plurality of sensors (9), where the signals represent the hopper ash levels in each of the plurality of hopper fields (1) for each of the plurality of passes () and an analyzing unit (8) configured to analyze ESP hopper ash levels for each ESP hopper field in each pass and generating one of first, second or third relay output through a relay card (7).
In a preferred embodiment, the relay outputs carry alarm signals that indicate to the operator to evacuate the affected hopper fields, reduce the boiler load and isolate the affected pass, or trip the boiler based on whether two-third of first three ESP hopper fields among the plurality of ESP hopper fields have high

hopper ash levels in one pass or one/two passes or more than two passes respectively.
The above and additional advantages of the present invention will become apparent to those skilled in the art from a reading of the following detailed description when taken in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
The drawings refer to embodiments of the invention in which:
FIG.1 is a block diagram illustrating an ESP hopper ash level monitoring system according to an embodiment of the present invention.
FIG.2 is a block diagram illustrating control schematic of a micro-controller based control system connected to each pass of ESP fields through digital input buffer card and relay output meant for pre warning the boiler operator according to an embodiment of the present invention.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION
Although the disclosure hereof is detailed and exact to enable those skilled in the art to practice the invention, the physical embodiments herein disclosed merely exemplify the invention which may be embodied in other specific structure. While the preferred embodiment has been described, the details may be changed without departing from the invention, which is defined by the claims.
It will be apparent, however, to one of ordinary skill in the art that the present invention may be practiced without specific details of the well known components and techniques. In other instances, well known components or techniques have not been described in detail but rather in Figures in order to

avoid unnecessarily obscuring the present invention. Further specific numeric references should not be interpreted as a literal sequential order. Thus, the specific details set forth are merely exemplary. The specific details may be varied from and still be contemplated to be within the scope of the present invention. The features discussed in an embodiment may be implemented in another embodiment.
Moreover, occasional references to the conventional systems for monitoring ash levels are made in order to better distinguish the present inventive disclosure discussed later in greater detail. Few of the details pertaining to the systems disclosed in the invention are well-known in the art, and therefore, are described herein only in the detail required to fully disclose the present invention.
Improving upon the conventional techniques discussed at length above (background), in the present disclosure the novel and inventive system for monitoring ash levels as shown in Figures 1-2 clearly makes the present system advantageous over the existing arts as would also become clearer to the knowledgeable in the art with the particulars of the aforesaid techniques being described below in greater detail.
In Fig.01, the complete overview of the invention set up is shown. In the figure, Block 01 shows a typical n fields ESP hoppers. Generally ESP fields are divided into passes which are numbered Pass A, B C…etc. Each pass has equal number of fields. So Pass A can have 6 fields or 8 fields etc. and there will be ash hopper corresponding to each field below it.
The block number 01 represents the Hopper under Electrostatic Precipitator which is used to collect the ash powder deposited on electrodes of the ESP. These ashes are made to fall down inside the Hopper with help of rapping system which raps the Collecting Electrode and Emitting Electrode of the ESP where the dusts are deposited. There is level sensor to measure the ash level

inside the hopper mounted on the wall of each hopper which will measure Ash level high and Ash level low. The Signal of the sensor is sent to block 02 of fig 01 which is the control unit of the invented system.
The block 02 of fig 01 represents the main control unit of the invented system. It consists of a microcontroller based controller/analyzing unit, a digital buffer card & digital relay card. The buffer card is used to receive the signal from the field and the relay card will be used to give digital output which will further be used for alerting the boiler operator.
The block 03 of fig 01 represents the warning system at UCB i.e. main control room. The relay output of block 02 of fig 01 will be terminated in the boiler panel and all the related warning will be displayed through DCS.
The warnings are related to ESP hopper levels. There are basically three warnings which are as below-A. In each Pass if it is found that two-third of first three fields hoppers are either high alarm i.e., ash has accumulated to a level higher than the sensor level inside the hopper OR under voltage i.e., the voltage in the ESP field has dropped below a pre-defined level for example, 10% of the rated voltage due to leakage through the ash due to high level in the hopper, then it will warn the operator to evacuate the hoppers immediately so that the hoppers may not get overloaded.
B. If condition as ‘A’ occurs for One or Two Passes, it will advise boiler operator to reduce boiler load accordingly and isolate the affected ESP pass to prevent it from further Ash build up and consequently to prevent it from collapse in case of overloading.

C. If condition as ‘A’ occurs for more than two Passes, it will advise to trip the boiler itself so as to avoid catastrophic damages that can occur due to over buildup of Ash level above the hopper.
Fig 02 represents control schematic of a micro-controller based control system connected to each pass of ESP fields through digital input buffer card and relay output meant for pre warning the boiler operator according to the invention.
Herein, block 04 shows the input from each pass i.e. Ash level status of each hopper of the passes is being sent to digital input buffer card through RS485 communication cable.
Block 05 of fig 02 represents main control and monitoring system of the invention. Here the inputs from the each pass are being received by controller (block 08) through digital input buffer card (block 06) and are analyzed by the control logic program which is done inside the controller. After analyzing the inputs, the controller will give output in the form of relay output (block 07) which will further be sent to main control room to alert the boiler operator to take suitable action as explained in detail in block 03 of fig 01.
The foregoing is considered as illustrative only of the principles of the invention. Furthermore, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described. While the preferred embodiment has been described, the details may be changed without departing from the invention, which is defined by the claims.

We Claim:
1. A system for monitoring abnormal ash levels in Electrostatic Precipitators
(ESP) Hoppers divided into plurality of passes with each of the plurality of
passes having plurality of ESP Hopper fields, the system comprising:
a plurality of sensors (9) configured to measure hopper ash level in the plurality of the hoppers in each pass;
a control unit (5) comprising:
a plurality of input buffer cards (6) configured to receive signals from the plurality of sensors (9), wherein the signals represent the hopper ash levels in each of the plurality of hopper fields (1) for each of the plurality of passes,
an analyzing unit (8) configured to analyze ESP hopper ash levels for each ESP hopper field in each pass and generating one of first, second or third relay output through a relay card (7);
a DCS in a control room for displaying one of the first, second or third relay output.
2. The system as claimed in claim 1, wherein the first relay output is generated when two-third of first three ESP hopper fields among the plurality of ESP hopper fields in one pass has high hopper ash level, and wherein the first relay output carries an alarm signal to evacuate the plurality of ESP hopper fields in said one pass.
3. The system as claimed in claim 1, wherein the second relay output is generated when two-third of first three ESP hopper fields among the plurality of ESP hopper fields in each of one or two passes have high

hopper ash level, and wherein the second relay output carries an alarm signal to isolate said one or two passes.
4. The system as claimed in claim 1, wherein the third relay output is generated when two-third of first three ESP hopper fields among the plurality of ESP hopper fields in each of more than two passes have high hopper ash level, and wherein the second relay output carries an alarm signal to trip the boiler.
5. The system as claimed in claim 1 is configured to act as an interlock between the boiler and the ESP, wherein the system is positioned in ESP control room or in boiler unit control room (UCB).