CLIAMS:We Claim:

1. A NRV Flap assembly for installation at blower discharge outlet to air duct line comprising:
non return valve flap cover comprising of peripheral dimensions matching the blower discharge outlet and being of weighted durable material adapted for a hinged operative connection whereby the flap cover is lifted up during blowing against its own weight to allow the blow of air into the air duct line and when blower is stopped the flap cover drops under its weight and fixes with sealing effect with respect to the blower opening thereby preventing any reverse rotation of blower by effective blocking back pressure in line.

2. A hinged NRV Flap assembly as claimed in claim 1 comprising,
A hinge unit comprising
A base securable to a fixture on top of the blower outlet with a rotatable hinge supported thereon;
A connecting member operatively connected to said rotatable hinge at one end and a spaced apart flap cover at its other end;

said flap cover disposed with respect to said hinge connecting member and spaced from rotatable hinge such as to enable lifting up during blowing against its own weight to allow the blow of air into the air duct line and when blower is stopped the flap cover dropping under its weight and abuttedly fixing with respect to the blower opening thereby preventing any reverse rotation of blower by effective blocking back pressure in line.

3. A hinged NRV Flap assembly as claimed in anyone of claims 1 or 2 wherein said flap cover is suitably weighted for the purpose and obtained of combination of rubber and a metal.

4. A hinged NRV Flap assembly as claimed in claim 3 wherein said flap cover is circular and obtained of rubber and a metallic disc inside rubber to facilitate the cooperative opening and closing of the blower outlet.

5. A hinged NRV Flap assembly as claimed in anyone of claims 1 to 4 wherein said connecting member at its top end connected to said hinge member supported with respect to said fixture allowing smooth swinging motion of said flap connected at the other end of said connecting member.

6. A hinged NRV Flap assembly as claimed in anyone of claims 1 to 5 , wherein said flexible circular flap is made of Rubber or Rubber-polymer material.

7. A hinged NRV Flap assembly as claimed in anyone of claims 1 to 6 , wherein said space between said base with hinge and the flap is based on the weight of the flap facilitating the opening and closing action based on the blower operation.

8. A hinged NRV Flap assembly as claimed in anyone of claims 1 to 7 wherein said flap cover comprise circular shaped cut out flat portion with rejection of any distorted portion obtained of any conventional synthetic rubber based and a metallic disc inside rubber NRV flap to facilitate reusability of even damaged distorted conventional NRV flaps.

9. A process for the manufacture of NRV Flap assembly for installation at blower discharge outlet to air duct line as claimed in anyone of claims 1 to 8 comprising:
non return valve flap cover with separate hingable connector for connection to a fixture over the blower outlet comprising
providing a non return valve flap cover with peripheral dimensions matching the blower discharge outlet and being of weighted durable material ;
providing a rotatable hinge adapted for rotatable fixing with respect to a fixture;
providing a connecting member operatively connected to said rotatable hinge at one end and a spaced apart connection to said non return valve flap cover at its other end.

10. A process as claimed in claim 9 wherein said non return flap cover is obtained of damaged conventional type single piece flap by generating a circular shaped cut out flat portion with rejection of any distorted portion of said conventional synthetic rubber based and a metallic disc inside rubber NRV flap to facilitate reusability of even damaged distorted conventional NRV flaps.

Dated this the 6th day of July, 2015
Anjan Sen
Of Anjan Sen & Associates
(Applicants Agent)
,TagSPECI:FIELD OF THE INVENTION

The present invention relates to an improved NRV flap configuration free of distortion and damage for blower discharge to air duct for supplying warm air to kiln ensuring desired sealing effect when the blower comes in standby mode. More importantly, the present invention is directed to provide a NRV flap configuration comprising metal hinge portion at top and a rubber/polymer based flap at the bottom to effectively seal the blower discharge opening free of any distortion. Advantageously, the NRV flap configuration facilitate reuse of distorted used rubber/synthetic material based conventional NRV flap utilizing the undistorted portion of flap combining with hinged mounting to ensure effective sealing of the duct line. The hinged NRV flap configuration favour complete sealing of discharge opening when blower is in standby or switch off mode avoiding reverse rotation of blower due to back pressure of duct and consequent damages, in a simple, cost effective and user friendly manner and reducing/eliminating plant down time.

BACKGROUND OF THE INVENTION

NRV flap is a type of non return valve that normally allows gas and specifically normal air, to flow through it in only one direction and is mounted in discharge line of air blower. It prevents the reverse rotation of the blower when blower unit is stopped, as Back pressure in line may cause the reverse rotation. The flap is made with rubber stamp and metal frame inside.

The currently used design, conventional type of NRV flap is fully made up of Rubber or rubber polymer, as it has a tendency to distort in continuous flow of air which is warm to some extent and due to the continuous flow of air the flap gets distorted. The distortion occurs at the point/line of repeated flexure of the flap as and when warm air is blown under pressure to the duct. When the blower stops, which operates on cycles, due to the distorted shape, the flap does not seal the discharge line which results in the back pressure and consequent reverse rotation of blower occurs which is not acceptable in the operation of blower as the pressure suddenly drops inside the Kiln which directly affects the production of plant.

Thus the existing NRV flap being made up of a Material Viton (brand of synthetic rubber) which has a tendency to distort under continuous flow of hot air and it does not regain its original shape, which resulting in back pressure in the duct line when the blower is in standby mode (due to distorted shape there is always a gap and there is no sealing effect of the flap for which it is meant for). As a result the distorted flap have to be replaced with a new one and regular frequency which is a costly affair. Moreover, a substantial time is required by maintenance person for dismantling and re installation of a new flap causing downtime of plant.

Due to Back Pressure in duct line the Blower may rotate in reverse direction due to which
• The V-Belts that connects the normal electrical motor driver to the blower shaft may suddenly break and disconnect the blower from its driving unit;
• The electrical power source supplying the electrical motor driving unit may suddenly fail – causing a “break down” and a break down may directly affect the production of plant.

The continuous flow of warm air results in the distortion of the NRV flap, as the rubber flap gets distorted there is always a gap that does not solve the sealing purpose. Different type of rubber polymers were used but it has only shown a small increase in life of the flap i.e. the distortion is only delayed a little bit, but the distortion would take place for sure on prolonged use. The existing NRV flap does not have the property to regain its shape after the external force i.e. air flow is stopped, resulting in improper sealing.

There has been thus a persistent need in the art to developing NRV flaps capable effective sealing of air duct line from blower in spite of prolonged use which can be reconfigured from used NRV flap in a simple and cost effective yet reliable manner, to completely avoid revered rotation of blower due to back pressure of duct when the blower remains in standby mode.

OBJECTS OF THE INVENTION

The basic object of the present invention is directed to provide NRV flaps for effective sealing of discharge air duct line from blower with longer operating life free of any distortion of flap due to repeated operation.

A further object of the present invention is directed to provide NRV flaps for effective sealing of discharge air duct line from blower wherein said NRV flap shall be composed of a metallic hinged portion at top and a rubber/polymer based bottom flap portion detachably connected to said hinge to cover the blower discharge opening supplying air to duct line.

A further object of the present invention is directed to provide NRV flaps for effective sealing of discharge air duct line from blower wherein said NRV flaps can be reconfigured and developed using undamaged portion of used NRV flaps thus saving huge cost.

A further object of the present invention is directed to provide NRV flaps for effective sealing of discharge air duct line from blower wherein the flap portion can smoothly and freely swing/rotate against the metallic hinged connection without causing any distortion of the rubber/polymer based flap portion favouring extended reliable operation.

A still further object of the present invention is directed to provide NRV flaps for effective sealing of discharge air duct line from blower which will ensure that no air leakage takes place and totally avoid reverse rotation of blower due to back pressure of sir duct line when the blower remains in standby mode.

A still further object of the present invention is directed to provide NRV flaps for effective sealing of discharge air duct line from blower which would be mounted with simple hinged connection to favour easy and faster installation and repair/replacement.

A still further object of the present invention is directed to provide NRV flaps for effective sealing of discharge air duct line from blower which would not get distorted due to opening and closing repeatedly on cyclic operation of blower while handling warm air.

A still further object of the present invention is directed to provide NRV flaps for effective sealing of discharge air duct line from blower which would not cause sudden pressure drop in kiln and resulting disruption in production.

A still further object of the present invention is directed to provide NRV flaps for effective sealing of discharge air duct line from blower which would avoid breakdown of blower and associated down time of production in steel plant.

SUMMARY OF THE INVENTION

The basic aspect of the present invention is directed to a NRV Flap assembly for installation at blower discharge outlet to air duct line comprising:
non return valve flap cover comprising of peripheral dimensions matching the blower discharge outlet and being of weighted durable material adapted for a hinged operative connection whereby the flap cover is lifted up during blowing against its own weight to allow the blow of air into the air duct line and when blower is stopped the flap cover drops under its weight and fixes with sealing effect with respect to the blower opening thereby preventing any reverse rotation of blower by effective blocking back pressure in line.

A further aspect of the present invention is directed to a hinged NRV Flap assembly comprising,
a hinge unit comprising
a base securable to a fixture on top of the blower outlet with a rotatable hinge supported thereon;
a connecting member operatively connected to said rotatable hinge at one end and a spaced apart flap cover at its other end;

said flap cover disposed with respect to said hinge connecting member and spaced from rotatable hinge such as to enable lifting up during blowing against its own weight to allow the blow of air into the air duct line and when blower is stopped the flap cover dropping under its weight and abuttedly fixing with respect to the blower opening thereby preventing any reverse rotation of blower by effective blocking back pressure in line.

A still further aspect of the present invention is directed to a hinged NRV Flap assembly wherein said flap cover is suitably weighted for the purpose and obtained of combination of rubber and a metal.

A still further aspect of the present invention is directed to a hinged NRV Flap assembly wherein said flap cover is circular and obtained of rubber and a metallic disc inside rubber to facilitate the cooperative opening and closing of the blower outlet.

Yet another aspect of the present invention is directed to a hinged NRV Flap assembly wherein said connecting member at its top end connected to said hinge member supported with respect to said fixture allowing smooth swinging motion of said flap connected at the other end of said connecting member.

According to an aspect of the present invention directed to said hinged NRV Flap assembly, wherein said flexible circular flap is made of Rubber or Rubber-polymer material.

A further aspect of the present invention is directed to a hinged NRV Flap assembly, wherein said space between said base with hinge and the flap is based on the weight of the flap facilitating the opening and closing action based on the blower operation.

A still further aspect of the present invention is directed to a hinged NRV Flap assembly wherein said flap cover comprises circular shaped cut out flat portion with rejection of any distorted portion obtained of any conventional synthetic rubber based and a metallic disc inside rubber NRV flap to facilitate reusability of even damaged distorted conventional NRV flaps.

Yet another aspect of the present invention is directed to a process for the manufacture of NRV Flap assembly for installation at blower discharge outlet to air duct line comprising :

non return valve flap cover with separate hingable connector for connection to a fixture over the blower outlet comprising

providing a non return valve flap cover with peripheral dimensions matching the blower discharge outlet and being of weighted durable material ;

providing a rotatable hinge adapted for rotatable fixing with respect to a fixture;

providing a connecting member operatively connected to said rotatable hinge at one end and a spaced apart connection to said non return valve flap cover at its other end.

A further aspect of the present invention is directed to said process wherein said non return flap cover is obtained of damaged conventional type single piece flap by generating a circular shaped cut out flat portion with rejection of any distorted portion of said conventional synthetic rubber based and a metallic disc inside rubber NRV flap to facilitate reusability of even damaged distorted conventional NRV flaps.

The objects and advantages of the present invention are described hereunder in greater details with reference to the following accompanying non limiting illustrative drawings.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

Figure 1: shows the front view and side view of the conventional NRV flap indicating its size and shape, location of holes for mounting on blower discharge end and the point of occurrence of distortion in service.

Figure 2: is the schematic view of the blower unit with discharge line with conventional NRV flap showing location of flap in closed position when blower is in standby mode and enlarged view showing NRV flap in open position when blower is in operational mode.

Figure 3(a) to 3(c): are the photographic images of the conventional NRV flap in original & distorted condition after repeated use causing failure of sealing action.

Figure 4(a) to (c): show the components involved in improved NRV flap mounting system according to the present invention to avoid distortion of NRV flap wherein (a) shows the metal hinge components comprising, metal base plate, nuts, metal rod, suspended metallic flap holding plate;(b) the assembly of hinge with flap holding plate;(c) circular shaped flap with central hole for bolt connection with flap holding plate.

Figure 5(a): shows the schematic assembly view of the metallic hinge with the rubber/polymer based circular flap according to the present invention in ready for mounting on blower discharge.

Figure 6: is the schematic view of conventional used NRV flap showing how it can be reused for the purpose of metal hinge based NRV flap mounting according to the present invention.

Figure 7:is the schematic view of the hinged mounting based NRV flap arrangement according to the present invention ensuring improved sealing avoiding distortion of flap showing the mounting of the flap on blower discharge end connected to air duct and its opening and closing positions.

DETAILED DESCRIPTION OF THE INVENTION WITH REFERENCE TO THE ACCOMPANYING DRAWINGS

The present invention is directed to provide an improved NRV flap configuration for effective sealing of discharge air duct line from blower with longer operating life free of any distortion of flap due to repeated operation.

NRV flap is a type of non return valve that normally allows gas and specifically normal air, to flow through it in only one direction and is mounted in discharge line of air blower. It prevents the reverse rotation of the blower when blower unit is stopped, due to back pressure of duct.

Accompanying Figure 1 shows the front view and side view of the conventional NRV flap indicating its size and shape, location of holes for mounting on blower discharge end and the point of occurrence of distortion in service. It is to be noted that the conventional NRV flap is directly mounted on blower end by bolting through these holes provided at the top of the flap itself. Importantly no other component is used for such mounting of the flap.

Accompanying Figure 2 is the schematic view of the blower unit with discharge line with conventional NRV flap showing location of flap in closed position when blower is in standby mode and enlarged view showing NRV flap in open position when blower is in operational mode. As already described herein before that the conventional type of NRV flap being fully made up of Rubber or rubber polymer, has a tendency to distort due to the continuous flow of warm air. The distortion occurs at the point/line of repeated flexure of the flap as and when warm air is blown under pressure to the duct.

The material of flap is rubber or rubber polymer and a metallic disc inside rubber, as the rubber flap is fastened in the discharge line and only the part where the bolts are fastened restrict the motion of the upper part of flap, whereas the bottom part moves from closed(Position A) to open (Position B)positions. As the blower is operated in cycles and hence when the cycle completes, the blower comes to a standby mode, this is when the Flap should return back from B point to A and solve the desired sealing purpose. But due to operation of Blowers in number of cycles as well as when the blower is in ON mode the flap is continuously stays to be in B Point as the continuous flow of warm air is observed, resulting in permanent distortion of rubber Flap.

Accompanying Figure 3(a) to 3(c) are the photographic images showing the conventional NRV flap in distorted condition after repeated use causing failure of sealing action. The current conventional type flap design is shown in the above photographs. Figure 3(a) shows new NRV unused Flap, which is fully made up of Rubber or rubber polymer, having a tendency to distort in continuous flow of air which is warm to some extent and due to the continuous flow of air, the flap gets distorted as shown in the above photographs Figures 3(b) & 3(c). As a result when the blower stops, due to the distorted shape, the flap does not seal the discharge line which results in the back pressure and the reverse rotation occurs which is not acceptable in the operation of blower as the pressure suddenly drops inside the Kiln which directly affects the production of plant.

In order to avoid such distortion of NRV flap and resultant failure of sealing action between blower discharge and duct line when blower is in standby or switch off mode, an improved NRV flap configuration involving metallic hinged based mounting arrangement has been developed by way of the present invention.

Accompanying Figure 4(a) to (c) show the components involved in improved NRV flap mounting system according to the present invention to avoid distortion of NRV flap wherein (a) shows the individual components that forms the metal hinge comprising, metal base plate(1), nuts(3), metal rod(2), suspended metallic flap holding plate(4);(b) the assembly of hinge with flap holding plate;(c) circular shaped flap(5) which is made of rubber polymer material with a central hole for bolt(6) connection with flap holding plate(4).

Accompanying Figure 5(a) shows the schematic assembly view of the metallic hinge with the rubber/polymer based circular flap according to the present invention in ready for mounting on blower discharge. It can be found in the NRV flap mounting according to the invention the main technical feature is the metallic arrangement which has to be fabricated once only for any of the blowers, as the motion of flap is only from closed position (point A) to open position (point B), the motion here will be smooth & there will be no point of distortion as the hinge effect will smoothen the operation. No special things are required, as the metallic arrangement can be fabricated with just two nuts (3), a piece of Rod (2) which can run smooth in these nuts (3), the nuts are welded to the base plate (1) which is a 3 mm thick MS sheet of 31mm x 130mm size having two holes 10mm dia at 90mm spacing along its centre line. A MS plate(4) of size 125mm x 40mm x3mm is attached to the centre of rod(2) at top for holding a 10mm thick flap with plate(4) with the help of a bolt(6) fastened at the center. The fabrication of the modified metallic hinge arrangement is done by welding. The flap (5) is made of rubber polymer material and is of circular shape of size to ensure perfect sealing of blower discharge opening. The NRV flap (5) is fixed at its central hole to the bottom hole of holding plate (4) with a bolt (6). In this assembly a selective gap of 112 to 115 mm is maintained between the hinge and the flap such that swing motion of flap from close to open position can be smoothly achieved without causing distortion of the flap and also a complete sealing is achieved in the closed position of flap when the blower is in standby mode or switch off mode, due to the gravity force aided by the weight of the metallic flap holding plate (4).

As the effective sealing area is the only important part of a NRV flap and in a conventional used flap this sealing area remains substantially usable, the NRV flap configuration of the present invention favour utilization of the undistorted portion of the conventional used flap by removing the distorted top portion such that the circular bottom potion obtained can be used to achieve a 99% of sealing of air in the discharge end while the blower is in standby mode or switched off mode. The procedure of reuse of conventional distorted flap for the purpose of present invention has been shown in accompanying Figure 6. This reutilization of conventional NRV flap in the present invention by combining with metallic hinge portion leads to substantial saving in material cost. In this drawing, it is shown that only the Flap bottom part will be reused and the part which is distorted (where fixing arrangement is given) will have to be cut and removed. The metallic hinge arrangement have to be fabricated to suit the sealing and the circular bottom part of distorted flap can be re utilized, resulting extended life of newly configured flap so obtained.

Accompanying Figure 7 is the schematic view of the hinged mounting based NRV flap arrangement according to the present invention ensuring improved sealing avoiding distortion of flap showing the mounting of the flap on blower discharge end connected to air duct and its opening and closing positions. In this NRV flap configuration, the movement of the flap from open(position B) during blower on condition to the flap closed(position A) during blower standby condition can be smoothly implemented due to the metallic hinge provision with a clear gap between the hinge and the flap. No external force will be required for the flap to get back in sealing position (i.e. position A). Advantageously, there occurs no distortion of the circular flap which is attached to the flap holding plate due to its transition from open to closed positions. Moreover, the metallic flap holding plate enable complete closing of the flap with blower discharge opening due to the weight of the metal part under gravity ensuring desired sealing, not allowing back pressure of duct line to cause reverse rotation of blower or sudden drop in kiln pressure.

It is thus possible by way of the present invention to provide a hinged NRV flap assembly configuration for installation at blower discharge to air duct line for supplying air to kiln wherein the flap ensure complete sealing of the discharge opening when the blower is in standby or switch off mode free of any distortion during operation and thus avoid reverse rotation of blower due to backpressure of duct line or sudden drop in pressure in kiln and associated down time of plant. The hinged NRV flap assembly configuration according to the present invention thus achieves the following advantages in blower operation:

1. The old NRV flap can be used instead of a new one resulting cost savings.
2. Once the arrangement is made can be used for a long duration of time without any high cost of maintenance.
3. The time required for changing a flap will also be reduced.
4. 99% sealing can be achieved.
5. No external force will be required for the flap to get back in sealing position (i.e. position A).

We Claim:

1. A NRV Flap assembly for installation at blower discharge outlet to air duct line comprising:
non return valve flap cover comprising of peripheral dimensions matching the blower discharge outlet and being of weighted durable material adapted for a hinged operative connection whereby the flap cover is lifted up during blowing against its own weight to allow the blow of air into the air duct line and when blower is stopped the flap cover drops under its weight and fixes with sealing effect with respect to the blower opening thereby preventing any reverse rotation of blower by effective blocking back pressure in line.

2. A hinged NRV Flap assembly as claimed in claim 1 comprising,
A hinge unit comprising
A base securable to a fixture on top of the blower outlet with a rotatable hinge supported thereon;
A connecting member operatively connected to said rotatable hinge at one end and a spaced apart flap cover at its other end;

said flap cover disposed with respect to said hinge connecting member and spaced from rotatable hinge such as to enable lifting up during blowing against its own weight to allow the blow of air into the air duct line and when blower is stopped the flap cover dropping under its weight and abuttedly fixing with respect to the blower opening thereby preventing any reverse rotation of blower by effective blocking back pressure in line.

3. A hinged NRV Flap assembly as claimed in anyone of claims 1 or 2 wherein said flap cover is suitably weighted for the purpose and obtained of combination of rubber and a metal.

4. A hinged NRV Flap assembly as claimed in claim 3 wherein said flap cover is circular and obtained of rubber and a metallic disc inside rubber to facilitate the cooperative opening and closing of the blower outlet.

5. A hinged NRV Flap assembly as claimed in anyone of claims 1 to 4 wherein said connecting member at its top end connected to said hinge member supported with respect to said fixture allowing smooth swinging motion of said flap connected at the other end of said connecting member.

6. A hinged NRV Flap assembly as claimed in anyone of claims 1 to 5 , wherein said flexible circular flap is made of Rubber or Rubber-polymer material.

7. A hinged NRV Flap assembly as claimed in anyone of claims 1 to 6 , wherein said space between said base with hinge and the flap is based on the weight of the flap facilitating the opening and closing action based on the blower operation.

8. A hinged NRV Flap assembly as claimed in anyone of claims 1 to 7 wherein said flap cover comprise circular shaped cut out flat portion with rejection of any distorted portion obtained of any conventional synthetic rubber based and a metallic disc inside rubber NRV flap to facilitate reusability of even damaged distorted conventional NRV flaps.

9. A process for the manufacture of NRV Flap assembly for installation at blower discharge outlet to air duct line as claimed in anyone of claims 1 to 8 comprising:
non return valve flap cover with separate hingable connector for connection to a fixture over the blower outlet comprising
providing a non return valve flap cover with peripheral dimensions matching the blower discharge outlet and being of weighted durable material ;
providing a rotatable hinge adapted for rotatable fixing with respect to a fixture;
providing a connecting member operatively connected to said rotatable hinge at one end and a spaced apart connection to said non return valve flap cover at its other end.

10. A process as claimed in claim 9 wherein said non return flap cover is obtained of damaged conventional type single piece flap by generating a circular shaped cut out flat portion with rejection of any distorted portion of said conventional synthetic rubber based and a metallic disc inside rubber NRV flap to facilitate reusability of even damaged distorted conventional NRV flaps.

Dated this the 6th day of July, 2015
Anjan Sen
Of Anjan Sen & Associates
(Applicants Agent)

ABSTRACT

TITLE: A HINGED NRV FLAP ASSEMBLY FOR INSTALLATION AT BLOWER DISCHARGE OUTLET TO AIR DUCT LINE.

There is provided an improved NRV flap assembly configuration for installation at blower discharge to air duct ensuring desired sealing effect when the blower comes in standby mode and is free of any distortion. The NRV flap assembly is a combination of a metal hinge portion at top and a rubber/polymer based flap at the bottom to effectively seal the blower discharge opening free of any distortion. Advantageously, the proposed NRV flap configuration allow reuse of undistorted portion of conventional rubber-polymer based NRV flap thus saving cost. The hinged NRV flap assembly configuration involves a hinged operative connection whereby the flap cover is lifted up during blowing against its own weight to allow the blow of air into the air duct line and when blower is stopped the flap cover drops under its weight and fixes with sealing effect with respect to the blower opening thereby preventing any reverse rotation of blower by effective blocking back pressure in line.
(Figure 7)