WO2012001701A2

WO2012001701A2 - Novel external flushing and lubrication of top/upper bearing of gear box of coal mill & improved filtration of oil

Info

Publication number: WO2012001701A2
Application number: PCT/IN2011/000395
Authority: WO
Inventors: Abhay Vishwas Ranade
Original assignee: Abhay Vishwas Ranade
Priority date: 2010-06-28
Filing date: 2011-06-13
Publication date: 2012-01-05
Also published as: WO2012001701A3

Abstract

The "Novel External Flushing and Lubrication of Top/Upper Bearing of Gear Box of Coal Mill & Improved Filtration of Oil" consisting of externally filtered oil (16) sent via hose(s) (15) through hole(s) (17) provided in Upper Bearing Housing Cover (13) for FLUSHING of contaminants and LUBRICATING Top Bearing (9,10,11) by oil spray/streams (18, 19, 20), and the system wherein the oil from the Gear Box (1) is pumped by a pump (2) to the Centrifuge Filter (3) which drops filtered oil in tank (4) from where the pump (5) sends filtered oil to Gear Box (1).

Description

Novel External Flushing and Lubrication of Top/Upper Bearing of Gear Box of Coal Mill & Improved Filtration of Oil

Field of the Invention

The present invention relates to flushing and lubricating system for upper bearing of gear box, and also relates to filtration of gear box oil. Background of the Invention

Presently, in a Coal Fired Thermal Power Station, that is a power plant, coal is crushed and then burnt to produce steam to run a turbine which is coupled to a generator. Mill/pulverizer is used to crush the coal and convert the coal into powder and this process is called "pulverizing". In India "pulverizer" is generally referred to as "Mill".

A typical bowl mill comprises of a bowl onto which the material to be pulverized, e.g. coal, is fed or supplied from above, in the centre of the bowl. The bowl rotates and is made to rotate. Inside this bowl are placed plurality of grinding rolls of journal assemblies placed equidistantly from each other. The grinding rolls are placed in such a way that they do not touch the bowl. Coal to be pulverized is allowed to enter between the bowl & grinding rolls. And thus the coal gets pulverized. The distance or space or gap between the bowl and the grinding roll and the pressure on grinding roll are adjusted externally by known methods depending on the quality and quantity of coal to be pulverized and fineness of pulverized coal desired. The above can be witnessed in any coal mill, e.g. a Raymond Bowl Mill. These Bowl-Mills around the world are called "CE" mills, wherein, "CE" stands for "Combustion Engineering" which is the name of the American Company which pioneered the manufacturing of such Mills.

In India most of these mills were introduced thru BHEL. These Mills are designated as XRS or XRP where,

X Stands for - 50, The Frequency of Electric Supply

R Stands for - Raymond

S Stands for - Suction

P Stands for - Pressurized

"Suction" & "Pressurized" are the two forms of conveying the pulverized material from the mill to the desired location. The desired location in a power plant is Furnace or Boiler. The "Suction" conveying has limitations & so only smaller mills have suction conveying. All large mills have "Pressurized" conveying. The XRS and XRP is followed by digits, e.g. XRS 623, XRP 623, XRP 763/783/803 etc., and the mills are so numbered for identification. First two digits denote Diameter of the Bowl in inches, & 3^rd digit denotes the number of grinding Rolls per Mill. PRIOR ART

The Bowl of the Mill is made to rotate. The Bowl is fixed at top end of a shaft called Vertical Shaft inside the mill. This vertical shaft extends from the bowl above, thru the bottom of the mill into a gear box below. In the gear box the vertical shaft is supported on a thrust bearing & passes thru a lower bearing housed in lower bearing housing. At the lower end of the vertical shaft is attached a mechanism which works like an oil pump which is referred to as 'Pump' or as Oil Pump' in the text below.

Just below the mill & in the gear box another bearing is placed around the Vertical Shaft. This bearing is called top/upper bearing. This Bearing will be referred to either as 'Upper Bearing' or as Top Bearing' in the text below. This upper bearing is housed in a housing called Upper Bearing Housing. This Upper Bearing Housing is covered by Upper Bearing Housing Cover. This upper bearing housing cover is equipped with oil seals. Between the two bearings, that is the upper bearing & the Lower Bearing is located a Geared Worm Wheel which is driven by a worm gear powered in turn by an electric motor.

In the Gear Box the oil Pump, Lower- Bearing, Lower Bearing Housing & Thrust Bearing remain fully submerged, and Worm- wheel & Worm-Shaft are partly submerged in oil & remain lubricated.

The Upper Bearing also requires Lubrication. This lubrication is offered by oil from the Gear Box itself.

Presently this "lubrication" of the Upper Bearing is achieved like this: There is a Pump attached at bottom end of the Vertical Shaft. When the Vertical Shaft is made to rotate, that is WHEN the mill is started, THEN ONLY this pump acts & pushes the oil below the vertical Shaft. There is a hole in centre of the Vertical Shaft and an inclined hole at top end of this centre hole in the Vertical Shaft. This inclined hole opens just above the Upper Bearing. After the mill starts the oil pushed by the pump below the Vertical Shaft gets pushed up through the centre hole and flows out of the inclined hole around the Vertical Shaft and on the Upper Bearing. This flow of oil on the Upper Bearing takes time and thus the lubrication of upper bearing starts AFTER some time of starting the mill.

In fact the situation of delay or absence of this lubrication is so serious and grave that there is a STATUTORY WARNING mentioned in all power plants to initiate action to STOP the mill if this lubrication has not commenced within 3 minutes of starting the mill.

The lube oil in the Gear Box which also lubricates the Top Bearing, however, gets contaminated. The CONTAMINANTS are mostly Pulverized Coal, ash and dust. Contamination of lube oil is a major problem in all industries more so in Coal Fired Thermal Power Stations, where the contaminants are produced (in the Mill) by the equipment (the Gear Box), which itself suffers most the brunt of the contamination.

DEFICIENCIES OF PRIOR ART

A. Oil gets contaminated.

B. Contaminants are abrasive.

C. Contaminants, when entering the Gear Box, first get into the Upper Bearing damaging the Bearing itself. These contaminants do not get flushed down.

D. The abrasive contaminants in the oil damage all internals of the Gear Box e.g. the lower bearing, the thrust bearing, bearings at both ends of the Worm Shaft, the Worm Shaft itself, the brass worm gear, the oil pump etc.

E. These abrasive contaminants in the Gear Box oil get transferred with the oil to the Upper Bearing causing damage to the Upper Bearing.

F. The pump loses its capacity due to abrasive nature of contaminants.

G. The reduction in capacity of pump causes the oil flow to the Upper Bearing to reduce over time, starving the Upper Bearing of lubricant.

H. Repair/Replacement/Maintenance of the pump attached to the Vertical Shaft is a MAJOR JOB frequently required to be done. It is very time consuming and very expensive by way of cost of spares, cost of replacement and loss of Power Generation due to non-availability of the mill ITSELF.

I. The contaminants result in formation of sludge. This sludge tends to block the holes in the Vertical Shaft, again affecting oil-flow to upper bearing.

J. FILTRATION IN MOST MILLS AND EXTERNAL FLUSHING & LUBRICATION IN ALL MILLS DO NOT EXIST for these types of mills. Object of the Present Invention: 1. To address and to answer and to solve the deficiencies of prior art.

2. The other object is to offer effective and positive flushing of the contaminants and lubrication to upper bearing with filtered oil at all times.

3. Yet another object is to achieve lubrication of Upper Bearing EVEN BEFORE the start-up of the Bowl Mill and this is the unique achievement. This is in reference to last but one para of the Prior Art.

4. Yet one more object is to make and offer an improved system for filtration of oil. Statement of the Present Invention:

According to this invention there is provided a "Novel External Flushing and Lubrication of Top/Upper Bearing of Gear Box of Coal Mill & Improved Filtration of Oil", which consists of externally filtered oil (16) sent via hose(s) (15) thru hole(s) (17) provided in Upper Bearing Housing Cover(13) for FLUSHING of contaminants & LUBRICATING Upper Bearing (9,10,11) by oil spray/streams (18,19,20); wherein further in this system contaminated oil from the Gear Box (1) is pumped by pump (2) to the Centrifuge Filter (3) which drops filtered oil in tank (4) from where the pump (5) sends filtered oil to Gear Box (1). DRAWINGS:

Brief Description of the Drawings

The invention will now be described with the help of drawings and figures. On the drawings and figures are mentioned numerals. The numerals are referred here below. The drawings/figures are schematic and non-restrictive examples. Drawings are Not to Scale.

Fig. [1]

Explains in simple block diagram, the various steps adopted for filtration of the Gear Box oil.

Fig.[2]

Explains the Novel Flushing and Lubrication of Top/Upper Bearing. Detail Description of the Invention

The foregoing objects of the present invention are accomplished and the problems and shortcomings associated with the prior art, techniques and approaches are overcome by the present invention as described below in the preferred embodiment.

This present invention is illustrated with reference to the accompanying drawings, throughout which reference numerals indicate corresponding parts in the various figures. These reference numerals are shown in brackets in the following description. In Fig.[l], Item (1) is the Gear Box containing oil. This oil needs to be kept clean and so it is required to be filtered. Item (2) is the Pump. This pump draws oil from the Gear Box & sends it to the Centrifuge Filter (3). This item (3) centrifugally filters the oil and drops the filtered oil into tank (4). The Pump (5) pumps the filtered oil from tank (4) back to Gear Box ( 1).

In Fig.2, Item (6) is Vertical Shaft. Item (7) is a hole drilled in the Centre of the Vertical Shaft (6). Item (8) is angular drilled hole. Item (9) is Inner Race of Top/Upper Bearing. Item (10) is one of the Rollers in cage of the Upper Bearing. Item (11) is outer Race of the Upper Bearing. Item (12) is Upper Bearing Housing. Item (13) is Upper Bearing Housing Cover. Item (14) is Rubber Seal(s). Item (15) is Delivery hose(s) to supply filtered oil (16) to the Upper Bearing Item Nos. (9, 10, 11). The Delivery hose(s) (15) is connected to Upper Bearing Housing Cover (13). Hole(s) (17) is provided in item (13). At the end of hole (17), there are further hole(s) provided which give oil spray and /or streams (18, 19, 20) to flush and lubricate Top Bearing item (9, 10, 11). In an embodiment, the system includes a MODULE comprising a three- way valve and a pair of strainers and pumps. Either pair of the strainer and the pump is alternately chosen at a time to draw, pump and send the filtered oil (16) via delivery hose(s) (15) through the hole(s) (17) provided in Upper Bearing Housing Cover (13) to flush the CONTAMINANTS & lubricate the Top Bearing (9, 10, 11) by Oil spray/streams (18, 19, 20) as shown in fig. 2.

Claims

I CLAIM:

1. A "Novel External Flushing and Lubrication of Top/Upper Bearing of Gear Box of Coal Mill & Improved Filtration of Oil" consisting of externally filtered oil (16) sent via hose(s) (15) through hole(s) (17) provided in Upper Bearing Housing Cover (13) for FLUSHING of CONTAMINANTS and LUBRICATING Top Bearing (9, 10, 11) by oil spray/streams ( 18, 19, 20).

2. The "Novel External Flushing and Lubrication of Top/Upper Bearing of Gear Box of Coal Mill & Improved Filtration of Oil" as claimed in Claim ( 1) above and further consisting of the system wherein the oil from the Gear Box (1) is pumped by a pump (2) to the Centrifuge Filter (3) which drops filtered oil in tank (4) from where the pump (5) sends filtered oil to Gear Box (1).