Claims:5. CLAIMS
1. A coal saving system (500) for a cement plant, wherein the system comprises of:
a plurality of supporting rollers (504);
a plurality of water-cooled lubricated bearing stations (502) for each of the supporting rollers (504);
a plurality of sensors (506) located inside the bearing station (102) for monitoring temperatures;
a formula is derived with the temperatures by exposing the support roller bearings (504) to kiln radiation and atmospheric conditions; and
the temperature values so derived from the formula are set as auto interlock to reduce coal firing and reduce radiation loss when the atmospheric temperature is high.

2. The coal saving system (500) as claimed in claim 1, comprises a computer implemented sub system for reducing the coal firing in the kiln.

3. The coal saving system (500) as claimed in claim 1, wherein the bearing station (502) of the rotary kiln is equipped with 6 supporting rollers and each roller has at least 2 water cooled oil lubricated bearing stations (502) for the operation/rotation of the kiln.

4. The coal saving system(500) as claimed in claim 1, wherein the support roller bearings (504) are exposed to kiln radiation and atmospheric condition for the purpose of monitoring the ambient temperature and the emitted radiation in real-time.

5. The coal saving system (500) as claimed in claim 1, wherein the bearing temperature follows a sinusoidal path over each day of operation and this variation is monitored through the computer implemented sub system.

6. The coal saving system(500) as claimed in claim 1, wherein the computer implemented sub system is set as auto interlock that help reduce coal firing and radiation loss when the atmospheric temp is high.

7. The coal saving system (500) as claimed in claim 1, wherein the cement is manufactured in the steps of lime stone mining and crushing (110), raw mill hydraulic raw press (215), coal mill (320) and pyro processing (425) in advanced manner.

8. The coal saving system (500) as claimed in claim 1, wherein major drivers involved in the machinery of the cement manufacturing system are equipped with variable frequency drives to achieve smooth process control, bump less speed variation, low power consumption and advanced diagnostics over fieldbus communication.

6. DATE & SIGNATURE

Dated 05th June 2019.

Signature

(SRINIVAS MADDIPATI)
IN/PA – 3124
Agent for Applicant
, Description:

4. DESCRIPTION
Technical Field of the Invention

The present invention relates to a cement production technology, more particularly relates to fuel optimization in a rotary kiln of the cement production system through an automatic computerized program by monitoring variation in process parameters due to variation in ambient temperature.

Background of the Invention

Cement manufacturing is a complex process that begins with mining and then grinding raw materials that include limestone and clay, to a fine powder, called raw meal, which is then heated to a sintering temperature as high as 14500 c in a cement kiln. In this process, the chemical bonds of the raw materials are broken down and then they are recombined into new compounds. The result is called clinker.

Clinker quality depends on raw material composition, which has to be closely monitored to ensure the quality of the cement. Excess free lime, for example, results in undesirable effects such as volume expansion, increased setting time or reduced strength. In general, the rotary kiln of a cement manufacturing plant consumes around 700kilo calorie of heat energy for producing 1kg of clinker which is further grinded with gypsum to produce cement.

For the production of such energy, the requirement of coal will be excessive along with the radiation loss and thus there is a need to develop a method or system by which the requirement of heat energy can be reduced which is proposed in this patent by monitoring the process parameters and its variation throughout the runtime of the kiln with the help of an automatic computerized program and put it as auto interlock so as to reduce coal firing and reduce radiation loss when the atmospheric temperature is high.
Brief Summary of the Invention

The present invention recognizes the limitations of the prior art and the need for systems and methods that able to aid users in a manner that overcomes these limitations.

According to an aspect of the present invention, a system for reducing fuel consumption in a coal fired rotary kiln of cement plant is disclosed.

In accordance with the aspect of the present invention, the coal saving system comprises of a plurality of supporting rollers; a plurality of water cooled lubricated bearing stations for each of the supporting rollers; a plurality of sensors located inside the bearing stations for monitoring temperatures; a formula is derived with the temperatures by exposing the support roller bearings to kiln radiation and atmospheric conditions; and the temperature values so derived from the formula are set as auto interlock to reduce coal firing and reduce radiation loss when the atmospheric temperature is high.

In accordance with the aspect of the present invention, the bearing station of the rotary kiln is equipped with 6 supporting rollers and each roller has at least 2 water cooled oil lubricated bearing stations for the operation/rotation of the kiln.

In accordance with the aspect of the present invention, the support roller bearings are exposed to kiln radiation and atmospheric condition for the purpose of monitoring the ambient temperature and the emitted radiation in real-time.

In accordance with the aspect of the present invention, wherein the bearing temperature follows a sinusoidal path over each day of operation and this variation is monitored through the computer implemented sub system.

In accordance with the aspect of the present invention, wherein the computer implemented sub system is set as auto interlock that help reduce coal firing and radiation loss when the atmospheric temp is high.

In accordance with the aspect of the present invention, wherein the cement is manufactured in the steps of lime stone mining, crushing, raw mill hydraulic raw press, coal mill and pyro processing in advanced manner.

In accordance with the aspect of the present invention, wherein major drivers involved in the machinery of the cement manufacturing system are equipped with variable frequency drives to achieve smooth process control, bump less speed variation, low power consumption and advanced diagnostics over fieldbus communication.

From a reading of the description above of the preferred embodiments of the present invention, modifications and variations thereto may occur to those skilled in the art. Therefore, the scope of the present invention is to be limited only by the claims of this invention.

Brief description of drawings

Example embodiments of the present invention are illustrated by accompanying drawings, wherein

FIG. 1 illustrates the lime stone crushing and mining process for crushing the limestone;

FIG. 2 illustrates the raw milling process where the limestone is fed with additives for the required mixture;

FIG. 3 illustrates the coal mill for the grinding of raw coal into a fine coal;

FIG. 4 illustrates the pyro-processing with a six stage preheater to produce clinker and

FIG.5 illustrates the bearing station of the rotary kiln for the proposed method of fuel optimization using a computerized program.

FIG. 6 illustrates the flowchart of the proposed monitoring program of the kiln.

Detailed description of the invention

The following description is merely exemplary in nature and is not intended to limit the present invention, applications, or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features.

Cement manufacturing is a complex process that begins with mining and then grinding raw materials that include limestone and clay, to a fine powder, called raw meal, which is then heated to a sintering temperature as high as 1450 0C in a cement kiln. In this process, the chemical bonds of the raw materials are broken down and then they are recombined into new compounds. The result is called clinker.

Clinker quality depends on raw material composition, which has to be closely monitored to ensure the quality of the cement. Excess free lime, for example, results in undesirable effects such as volume expansion, increased setting time or reduced strength. Several laboratory and online systems can be employed to ensure process control in each step of the cement manufacturing process, including clinker formation.

A conventional plant consists of around 700-800 motors. This constitutes to be a major power consumer so highly efficient IE3 standard motors are installed. These type of motors use less electricity, run cooler and lasts longer thereby improving efficiency and saving the power at same time.

Also most of the drives reach to maximum capacity based on the process condition using this system. This provides the margin for power reduction by running at appropriate speed instead of full speed. The major drivers in the production systems are equipped with variable frequency drive, so as to achieve smooth process control bump less speed variation, low power consumption and advanced diagnostics over fieldbus communication.

According to an exemplary embodiment of the present invention, a system (100) for reducing fuel consumption in a coal fired rotary kiln of cement plant is disclosed.

In accordance with the exemplary embodiment of the present invention, the coal saving system (500) comprises of a plurality of supporting rollers (504); a plurality of water cooled lubricated bearing stations (502) for each of the supporting rollers (504); a plurality of sensors (506) located inside the bearing stations (502) for monitoring temperatures; a formula is derived with the temperatures by exposing the support roller bearings (504) to kiln radiation and atmospheric conditions; and the temperature values so derived from the formula are set as auto interlock to reduce coal firing and reduce radiation loss when the atmospheric temperature is high.

In accordance with the exemplary embodiment of the present invention, the bearing station (502) of the rotary kiln is equipped with six (6) supporting rollers (504) and each roller has at least two (2) water cooled oil lubricated bearing stations for the operation/rotation of the kiln.

In accordance with the exemplary embodiment of the present invention, the support roller bearings (504) are exposed to kiln radiation and atmospheric condition for the purpose of monitoring the ambient temperature and the emitted radiation in real-time.

In accordance with the exemplary embodiment of the present invention, wherein the bearing temperature follows a sinusoidal path over each day of operation and this variation is monitored through the computer implemented sub system.

In accordance with the exemplary embodiment of the present invention, wherein the computer implemented sub system is set as auto interlock that help reduce coal firing and radiation loss when the atmospheric temp is high.

In accordance with the exemplary embodiment of the present invention, wherein the cement is manufactured in the steps of lime stone mining, crushing, raw mill hydraulic raw press, coal mill and pyro processing in advanced manner.

In accordance with the exemplary embodiment of the present invention, wherein major drivers involved in the machinery of the cement manufacturing system are equipped with variable frequency drives to achieve smooth process control, bump less speed variation, low power consumption and advanced diagnostics over fieldbus communication.

The overview of the proposed system of cement manufacturing process is illustrated below:
FIG. 1 illustrates the lime stone crushing and mining process (110) for crushing the limestone. As shown in FIG. 1, lime stone mining is carried out on a dedicated limestone mining area. These large boulders need to downsize before using it. For that, crushing of limestone using an impact crusher of 1200 ton/hour capacity. The limestone is crushed in 2 stages by using a primary crusher with 1200 kW motor and a secondary crusher with 1440kw motor capacities.

FIG.2 illustrates the raw milling process (215) where the limestone is fed with additives for the required mixture. As shown in FIG. 2, the crushed limestone from the limestone crusher is fed along with additives mainly include bauxite / redmud / feldspar / lithomer to achieve required chemistry of raw mix. This raw mix is fed to hydraulic roller press of dimensions 1920x1563 and 250 ton/hour grinding capacity. The mixture is again pressed in between 2 heavy rollers one movable and one fixed at high pressure of around 150 bar. At this high pressure the resultant material is fine powder which is taken away by suction of fan and stored in controlled flow silo of 15000 mt capacity in the form of raw meal. The fineness of material is ensured with the help of separator which rejects the coarse and fed back into the circuit.

FIG. 3 illustrates the coal mill (320) for the grinding of raw coal into a fine coal. As shown in FIG. 3, raw coal is grinded into fine coal by using coal mill. A vertical roller coal mill of 64 tons/hour capacity is used. Coal is grinded on a table and fine coal is stored on 2 separate bins namely kiln fine coal bin and pre calciner fine coal bin.

FIG. 4 illustrates the pyro-processing (325) with a six stage preheater to produce clinker. As shown in FIG. 4, the double string 6 stage preheater with specially designed cyclones stacked on each other is used for this process. Coal is major fuel for pyro process and it is fired at two different points i.e. kiln and precalciner. The inline calciner where the calcination process begins before raw meal enters the kiln. The raw meal from silo is the main feed for kiln. Before entering the kiln is preheated in a preheater. We have 6 stage preheaters wherein the material is dropped from top of preheater in a cyclonic movement due to presence special designed cyclones. Preheater fan of 3mw is installed to run hot air across the preheater from burning kiln furnace. Therefore hot air moves from bottom to top and material movement is from top to bottom resulting in heat exchange from air to material.

The reactions that take place during pyro processing as the temperature of the raw mix rises are as follows:
1. at 70 to 110 °c free water is evaporated.
2. at 400 to 600 °c clay like matter is decomposed into SiO2 and Al2O3; Dolomite (Ca Mg (CO3)2) decomposes to calcium carbonate (CaCO3), MgO and CO2.
3. at 650 to 900 °c - calcium carbonate reacts with SiO2 to form belite (Ca2SiO4) (also known as C2S in the cement industry).
4. at 900 to 1050 °c - the remaining calcium carbonate decomposes to calcium oxide (CaO) and CO2; and
5. at 1300 to 1450 °c - partial (20–30%) melting takes place, and belite reacts with calcium oxide to form Alite (Ca3O·SiO4) (also known as C3S in the cement industry).

Alite is the characteristic constituent of Portland cement. Typicall, a peak temperature of 1400–1450 °c is required to complete the reaction. The partial melting causes the material to aggregate into lumps or nodules, typically of diameter 1–10 mm. this is called clinker. The hot clinker next falls into a cooler which recovers most of its heat, and cools the clinker to around 100 °c, at which temperature it can be conveniently conveyed to storage. The cement kiln system is designed to accomplish these processes.

FIG.5 illustrates the bearing station (502) of the rotary kiln for the proposed method of fuel optimization using a computerized program. As shown in FIG. 5, coal is fired in the kiln at rate of around 10- 15 tons / hour maximum based on the burning zone temperature / kiln condition and clinker quality like liter weight / free lime and nodule size. The kiln emits heat radiation continuously as we fire inside the kiln. Heat radiation is high when atmospheric temp is low and heat radiation is low when atmospheric temp is high. The basic radiation loss is normally 10 % of total heat consumed in kiln system.

In order to reduce the aforementioned radiation losses and fuel consumption, the bearing station (502) of the rotary kiln is supported with 6 supporting rollers (504) and each roller (504) having two water cooled oil lubricated bearing stations. The temperature of bearing is monitored using temperature sensor (506) located inside the bearing station (502). The bearing temperature follows a sinusoidal path over each day of operation. The support roller bearings (504) are exposed to kiln radiation and atmospheric condition. An automatic computerized formula is developed to monitor these process parameters and put to use in the form of the auto interlock to reduce coal firing and radiation loss with the increase in atmospheric temperature.

FIG. 6 illustrates the flowchart of the proposed monitoring program of the kiln. As shown in the FIG.6, the average ambient temperature is calculated by considering the ambient temperatures of everyday and is noted down with the help of the temperature sensors located in the bearing station. Now when the actual temperature is found to be lesser, the radiation loss will be high. In such a case, the computerized formula which is set as auto interlock with the system reduces the coal firing whenever the atmospheric temp is high. The coal set point at this point will be taken by reducing 0.1 ton of coal from the actual coal required for the firing operation of the kiln by the proposed formula.