FIELD OF INVENTION:

The invention relates to an exhaust gas treatment system.

BACKGROUND OF THE INVENTION:

In today's market diesel engines are gaining momentum, by virtue of their unique characteristics such as high energy efficiency, high torque and low fuel consumptions. However, these benefits come with a trade-off. By virtue of property of the diesel fuel, the combustion happens at a very high temperature (around 600 °C). At such temperatures, the amount of Nitrogen Oxides (NOx) produced is very high.

In the SCR system, a 32.5 % aqueous urea solution (AdBlue®) is injected into the exhaust gas flow as a reactant. The metering control unit sprays a precise quantity of AdBlue® into the exhaust, based on various parameters such as engine speed, engine torque, exhaust temperature, ambient temperature etc

Selective Catalytic Reduction (SCR) is a proven technology to reduce nitrogen oxide emissions from combustion processes for vehicles. The AdBlue® (aqueous urea) is hydrolyzed into ammonia. In the presence of the SCR catalyst the ammonia converts NO and N02, in the exhaust, to nitrogen and water vapor. Careful control of urea injection ensures proper chemical reaction in the exhaust, thereby reducing nitrogen oxides (NOx) to the maximum possible extent.

SCR-Catalyst is installed in the exhaust path. It is designed to selectively reduce NOx among other emissions like CO, CO2, unburnt hydrocarbons etc. from the engine emissions.

The urea used in the Adblue is predominantly from a chemical industry, thereby giving rise to emissions during its synthesis, and polluting the environment.

OBJECT OF THE INVENTION:

The object of this invention is to make use of the natural urea for treatment of exhaust gases. The natural urea is available in the urine of herbivorous animals, especially cows. The urine from such animals, which is referred as natural urea in the rest of the document, is used as replacement for the Adblue solution for treating the exhaust gases. As the natural urea is used, all the environment related problems in manufacturing the urea chemically, are eliminated.

ADVANTAGES OF THE INVENTION:

Using the natural urea as replacement for the Adblue solution, provides a simple alternative for the Adblue in the exhaust gas treatment. By using the natural urea to treat the exhaust gases, the invention proposes a low cost, environment friendly alternative method for treating the exhaust gases.

BRIEF DESCRIPTION OF THE DRAWINGS:-

FIG. 1 shows a schematic of the invention
FIG. 2 shows a graph showing the reduction of NOx level during the
Experiment

DETAILED DESCRITPION OF THE INVENTION:

The present invention is described in the preferred embodiment as follows:-
FIG. 1 shows a schematic of an exhaust gas treatment system according to the invention. The exhaust gas treatment system 10 comprises an inlet 12 to receive the exhaust gases coming from the engine, an outlet 14 to send the exhaust gases out of the exhaust gas treatment system 10, a chamber 16 where the chemical reaction takes place, a tank 18 to store the natural urea, the urea supply path 20 and an electronic control unit 22 to control the supply of the natural urea from the tank 18.

The chamber 16 has a set of pipes 24 whose one end is closed. The other end of the pipes 24 is connected to the urea supply path 20. The pipes 24 are made of either clay or ceramic material. The material used to make the pipes 24 is porous in nature.
The pipes 24 are referred as urea percolating means in some part of this document.
A controlled quantity of natural urea is supplied from the urea tank 18 through the urea supply path 20 to the pipes 24 in the chamber 16. The urea gets accumulated in the pipes 24, as the other ends of the pipes are closed. As the pipes 24 are porous in nature, the natural urea stored in the pipes 24, percolates to the outer surface of the pipes 24.

The exhaust gases are guided into the chamber 16 through the inlet 12. The exhaust gases pass around the pipes 24 and come in contact with the outer surface of the pipes 24. As the natural urea has percolated to the outer surface of the pipes 24, the exhaust gases react chemically with the natural urea.

In the state of the art SCR systems, the chemical reaction takes place as below:
2NH3 + [ NO + NO2 ] 2 N2 + 3 H2O
( Natural urea ) ( exhaust emission ) ( Reaction products )
Similar chemical reaction takes place in the presence of natural urea.
The natural urea reacts with the NO and N02 gases in the exhaust gases to produce N2 and Water. Thus the harmful gases in the exhaust gases are reduced to harmless gas Nitrogen and water.

Careful control of urea supply ensures proper chemical reaction in the exhaust, thereby reducing nitrogen oxides (NOx) to the maximum possible extent. The ECU 22 keeps monitoring the exhaust gases in the inlet 12 and outlet 14. Depending upon the amount of NOx in the exhaust gases entering the chamber 16 and leaving the chamber 16, the ECU 22 controls the amount of natural urea to be supplied to the pipes 24 in the chamber by operating the valve 26 appropriately.

The ECU 22 also monitors the level of the natural urea available in the urea tank 18 and generates an indication when the natural urea is running low.
The use of pipes 24 is only for an illustration. Different structures may be used to supply the natural urea, for example, the structure may be in the form of a honey comb. When the structure is in the form of a honey comb, there are passages for the exhaust gases to pass through the honey comb structure. As the surface area provided for the chemical reaction in the honey comb is higher compared to the pipes 24, there may be increased efficiency in the reduction of the harmful gases.
Also it is possible that instead of the pipes 24, the hardware components in the present selective catalytic reduction (SCR) system may be used. The urea is replaced by the natural urea and the injection systems in the SCR system remain as it is. The natural urea is injected into the exhaust gases flowing through the exhaust path (12, 14) where the chemical reaction takes place.

Experimental results conducted in lab with natural urea show an approximate reduction of 31% in Nox levels when compared to without natural urea.

WE CLAIM:

1. An exhaust gas treatment system (10), the said exhaust gas treatment system using a solution which has properties close to natural urea.

2. An exhaust gas treatment system (10) according to claim 1 comprising :
-an exhaust inlet (12) to receive exhaust gases;
-an exhaust outlet (14) to send out the treated exhaust gases;
-a tank (18) to store natural urea;
-at least one urea percolating means (24);
-a supply path (20) to supply urea from the urea tank to the urea percolating
means (24);
-an ECU (22) to regulate the supply of natural urea to the urea percolating
means (24);
the said exhaust gas treatment system (10) adapted to reduce NOx level from
the said exhaust gases

3. An exhaust gas treatment system (10) according to claim 1 wherein the said natural urea is the urine from herbivorous animals.

4. An exhaust gas treatment system (10) according to claim 1 wherein the said natural urea is treated to increase its efficacy.

5. An exhaust gas treatment system (10) according to claim 1 wherein the said natural urea is treated by heating it.

6. An exhaust gas treatment system (10) according to claim 2 wherein the said urea percolating means (24) is made of material which is porous.

7. An exhaust gas treatment system (10) according to claim 2 wherein the said urea percolating means (24) is made of clay.

8. An exhaust gas treatment system (10) according to claim 2 wherein the said urea percolating means (24) is made of ceramic.

9. An exhaust gas treatment system (10) according to claim 2 wherein the said urea
percolating means (24) is in the shape of a pipe which has one end closed and
the other end connected to urea supply path.

10. An exhaust gas treatment system (10) according to claim 2 wherein the said urea percolating means (24) is in the shape of a honeycomb.

11. A method to treat exhaust gases, the said method comprising the steps:
- Receiving the exhaust gases
- Allowing the exhaust gases to chemically react with the natural urea