The present invention relates generally to rotary joints. More specifically, the present invention relates to a rotary joint to be used in paper and textile industries, which integrates one or more diagnostic and control features.

BACKGROUND OF THE INVENTION

Surface type heat exchangers are widely used in paper and textile industries to heat or cool products, such as papers or fabrics. Such heat exchangers typically include a heat transfer cylinder (or drum) and a thermally insulated material (also referred to as a thermal jacket) between which a heating or cooling medium is circulated. Depending on the application, the medium may be steam or water; however, any other media may also be used.

Rotary joints are used to introduce the heating or cooling medium inside the heat transfer cylinder or remove a condensate formed therein. A rotary joint is a critical device due to its function of simultaneous supply of steam and continuous removal of the condensate. A typical rotary join includes a housing that is rotatably mounted on a nipple that is concentric to the axis of rotation of the heat transfer drum. A suitable bearing, such as a carbon bearing, may be interposed therein. An annular carbon bearing itself acts as a sealing element between rotating dryer shaft and rotary joint stationary body and produces a fluid-tight environment.

For efficient operation of the rotary joint (and in turn of the heat exchanger), it is imperative that the sealing elements permit absolutely no leakage of the fluid. Further, the high pressure and temperature within the rotary joint often causes excessive seal wear. Due to the high pressure and temperature, the seal friction increases, thereby increasing the seal wear further. Sealing effectiveness is one of the key factors for smooth running of the dryer. Therefore, seal wearing is required to be monitored, reported and prevented to ensure trouble free production. In a typical application, multiple dryers are used in tandem and/or in parallel configurations. Various parameters, such as stem flow, differential pressure and temperature across these multiple dryers can be measured by using various known sensing mechanisms. Control of these parameters plays a critical role in successful dryer operation. For example, measuring and controlling the differential pressure across each dryer is critical for effective condensate removal from the dryers. The differential pressure across each dryer depends upon the type of siphon used, i.e., for example, low speed stationary siphons, rotary siphons, high speed stationary siphons, elbow siphons, spring loaded elbow siphons, or combinations thereof. It is often difficult to remove the condensate completely, especially when the differential pressures are low.

Moreover, in prior art rotary joints, the differential pressures and temperatures can only be controlled for multiple drums together, i.e., there is only a group control available. Since each individual dryer may operate at different working conditions, an individual control of these parameters is often desirable. For example, it is required to keep a higher differential pressure at the bottom dryers than at the top dryers for better condensate removal. Existing systems fail to provide an individual control of differential pressures and/or temperatures across different dryers.

In addition, in prior art rotary joints, the steam pressure and temperature measurements are performed by using conventional pressure and temperature gauges. These gauges are often located in places of the dryer that are not easily accessible to the operator because of the height of the dryers. It is therefore difficult to obtain the pressure and temperature readings. Finally, the measurements are often taken manually from time to time, and therefore, keeping and maintaining their record becomes a cumbersome task. Manual errors may also be involved in these measurements, and therefore, they are often incorrect. It is desirable to have a system to keep records of these measurements in an efficient and accurate manner.

In light of the foregoing, there exists a need for a rotary joint to be used in heat exchanger cylinders that can solve the above-mentioned problems of the prior art rotary joints. The rotary joint should be able to measure and control flow rates, differential pressures, temperatures and seal wear rates across individual dryers. Further, when multiple drums are involved, the system should facilitate individual measurement and control of these parameters.

SUMMARY OF THE INVENTION Various embodiments of the present invention provide an integrated rotary joint configured to be positioned between a fluid inlet, a condensate outlet and a rotary drum of a surface type heat exchanger for circulating a fluid medium into and out of the surface type heat exchanger. The integrated rotary joint includes a housing that has a radial bore that defines a fluid flow chamber therein. The fluid medium enters the fluid flow chamber from the fluid inlet and is carried into the rotary drum by way of the fluid flow chamber. A carbon bearing is fitted between the housing and a rotating dryer shaft extending outwardly from the rotary drum. This carbon bearing also acts as a sealing element and prevent leakage of the fluid medium from the integrated rotary joint. A stationary siphon extends from an inner surface of the rotary drum to the condensate outlet by way of the at least one annular sealing element, the at least one carbon bearing, and the fluid flow chamber. Further, various sensors such as pressure and temperature sensors are provided for measuring differential pressure and temperature at the fluid flow passage. A flow measurement mechanism is disposed at the fluid inlet for measuring a fluid flow rate. In addition, a wear detection means is in contact with the at least one annular sealing element, which detects a seal wear rate of the annular sealing element.

Preferably, the integrated rotary joint includes a remote monitoring system in

communication with the at least one pressure sensor, the at least one flow measurement mechanism, the at least one temperature sensor, and the at least one wear detection means. The remote monitoring system is configured to obtain values of the differential pressure, the fluid flow rate, the temperature and the seal wear rate from respective measurement mechanisms. The communication may be wired or wireless. The remote monitoring system includes a display for displaying the measured parameters to a user.

Preferably, the integrated rotary joint includes a vacuum creator disposed between the stationary siphon and the condensate outlet. The vacuum creator creates a pressure difference between the rotary drum and the condensate outlet by way of the stationary siphon, such that an easy removal of condensate from the condensate outlet is facilitated.

Preferably, the integrated rotary joint includes a sight glass for allowing a visual inspection of working conditions inside the integrated rotary joint.

DETAILED DESCRIPTION OF THE EMBODIMENTS OF THE INVENTION

The features of the present invention, which are believed to be novel, are set forth with particularity in the appended claims. Embodiments of the present invention will hereinafter be described in conjunction with the appended drawings provided to illustrate and not to limit the scope of the claims, wherein like designations denote like elements, and in which:

Fig.1 is across sectional view of a surface type heat exchanger including an integrated rotary joint, in accordance with an embodiment of the present invention;

Fig. 2 is an expanded cross sectional view of an integrated rotary joint, in accordance with an embodiment of the present invention; and

Fig. 3 is an expanded cross sectional view of an integrated rotary joint, in accordance with another embodiment of the present invention.

As used in the specification and claims, the singular forms "a", "an" and "the" include plural references unless the context clearly dictates otherwise. For example, the term "an article" may include a plurality of articles unless the context clearly dictates otherwise.

Those with ordinary skill in the art will appreciate that the elements in the Figures are illustrated for simplicity and clarity and are not necessarily drawn to scale. For example, the dimensions of some of the elements in the Figures may be exaggerated, relative to other elements, in order to improve the understanding of the present invention. There may be additional components described in the foregoing application that are not depicted on one of the described drawings. In the event such a component is described, but not depicted in a drawing, the absence of such a drawing should not be considered as an omission of such design from the specification. While the specification concludes with the claims defining the features of the invention that are regarded as novel, it is believed that the invention will be better understood from a consideration of the following description in conjunction with the drawings, in which like reference numerals are carried forward. Referring now to figures, more specifically to Fig. 1, cross sectional view of a surface type heat exchanger 100 that includes an integrated rotary joint 102, in accordance with various embodiments of the present invention, is shown. The surface type heat exchanger 100 includes a rotary drum 104, a cantilever stationary siphon 124, and a Teflon shoe 126. The rotary joint 102 includes a steam inlet 108, a condensate outlet 110, a housing 112, a fluid flow chamber 114, an annular carbon seal bearing 116, a vacuum creator 118, a variable length bracket 120, a flow measurement mechanism 122, and a sight glass 132.

The rotary drum 104 rotates about a horizontal axis 106. The rotary drum 104 forms a chamber therein, in which a heating or cooling medium is circulated. In an embodiment of the present invention, steam is used as a heating medium. Paper or textile web maybe formed on the outer surface of the rotary drum 104 for drying thereof. Steam enters the integrated rotary joint 102 through the steam inlet 108. The housing 112 forms the fluid flow chamber 114 therein, by way of which steam enters the rotary drum 104. A carbon bearing 116 is fitted between the rotary drum 104 and the integrated rotary joint 102, about a rotary shaft 130 of the rotary drum 104. The carbon bearing 116 acts as an annular seal, such that steam does not escape the rotary drum 104 and the integrated rotary joint 102.

When the steam is circulated inside the rotary drum 104, a condensate is formed at the bottom thereof. The stationary cantilever siphon 124 takes the condensate out by way of the Teflon shoe 126 and through the condensate outlet 110. An appropriate bore may be provided at the siphon for this purpose. The vacuum creator 118 creates vacuum at the condensate outlet 110 by using thermo compressor principle High pressure motive steam accelerates through a siphon nozzle (not shown). As it enters the suction chamber at supersonic speeds, it entrains and mixes with low pressure steam from the suction inlet 108. It crates low pressure region in the suction chamber, which helps suck condensate through siphon pipe. The resultant steam mixture then enters a convergent-divergent diffuser (not shown) where its velocity reduces, and its kinetic energy is converted to pressure. The steam discharged by the thermo compressor is then recycled into the process. This enables effective condensate removal, even at a very low differential pressure inside the rotary drum 104. The stationary cantilever siphon 124 does not rotate with the rotation of the drum and thus avoids siphon related problems occurring in the prior art systems. Further, dryer flooding may happen due to improperly maintained differential pressure in the rotary drum 104. This also exerts more force on the siphon pipe and results in a siphon failure. Steam leakage through the prior art rotary joints causes a major steam loss, as there is no control over the seal wear. Therefore, the integrated rotary joint 102 of the present invention includes a seal wear detection mechanism to detect and report the seal wear of the annular seal 116. This will further be explained in detail in conjunction with Figs. 2 and 3. The variable length bracket 120 facilitates an adjustment of the distance between the integrated rotary joint 102 and the rotary drum 104. Due to the seal wear, the distance between the integrated rotary joint 102 and the rotary drum 104 reduces and thus, there is a possibility of steam loss. In order to prevent this loss, the adjustment of distance is often required.

In an embodiment of the present invention, a sight glass 132 may be integrated in the rotary joint 102 to facilitate a visual inspection of the working conditions and monitoring thereof by an operator (for example, condensate removal can be observed through the sight glass). As the sight glass 132 is provided at the integrated rotary joint 102, an easy inspection is facilitated.

Referring now to Fig. 2, an expanded cross sectional view of the integrated rotary joint 102 of Fig. 1, in accordance with an embodiment of the present invention, is shown. The integrated rotary joint 102 of this embodiment includes a wired monitoring system 202. The integrated rotary joint 102 of Fig. 2 is similar in construction to that of the integrated rotary joint 102 of Fig. 1, and in addition includes one or more pressure sensors 204, one or more

temperature sensors 206, a flow meter 208 and seal wear detection means 210. The wired monitoring system 202 includes a display unit 212 and wired connections 214.

In an embodiment of the present invention, the one or more pressure sensors 204 are placed appropriately at the steam inlet 108 sideand measure the differential pressure at the integrated rotary joint 102. The differential pressure (dp) plays an important role in effective condensate removal from the rotary drum 104; therefore, its monitoring and control is essential. In addition, one or more temperature sensors 206 are also placed inside the fluid flow chamber 114. A flow measurement arrangement, such as a flow meter 208 can be placed at the steam inlet 108 to measure the flow rate thereat. A seal wear measurement means 210, scale/linear displacement sensors are fitted on stationary integrated rotary joint 102. This sensor is placed in contact with the annular seal 116 to measure the sealing wear thereof.

A skilled artisan will appreciate that although the pressure sensors 204 and the temperature sensors 206 are shown at their respective locations, it is for exemplary purposes only. The pressure sensors 204 and temperature sensors 206 can be integrated into one sensor arrangement, placed at an appropriate location in the integrated rotary joint 102.

The measurements obtained by the pressure sensors 204 or temperature sensors 206, flow meter 208 and seal wear measurement means 210 are sent to a central monitoring system (central coordinator) through wired connections 214. The central coordinator may include an electronic unit (not shown) and run simulation software that interprets these parameters and displays them at the display unit 212. Various trends and diagnostic data may be generated and displayed. The display unit 212 may be remotely situated from the integrated rotary joint 102, thus enabling easy viewing and control of various parameters associated therewith by a user. A skilled artisan will appreciate that the various parameters obtained from the integrated rotary joint 102 may be simulated by using a Supervisory Control arid Data Acquisition (SCAD A) system. Fig. 3 illustrates an expanded cross sectional view of the integrated rotary joint 102 of

Fig. 1, in accordance with another embodiment of the present invention. The integrated rotary joint 102 of this embodiment includes a wireless monitoring system 302. The integrated rotary joint 102 of Fig. 3 is similar in construction and working to that of the integrated rotary joint 102 of Fig. 1, and in addition includes a radio-frequency (RF) transmitter/receiver module 304 integrated into the rotary joint 102. A corresponding RF transmitter/receiver module (not shown) is located at the central coordinator unit. The two RF modules communicate wirelessly to exchange the data.

In a preferred implementation of the present invention, when a number of rotary surface heat exchangers are used in tandem or parallel together as a heat exchanger system (in applications such as paper and textile industries), measurement and control of parameters is provided at an individual rotary surface heat exchanger. In other words, the system of the present invention is provided at each integrated rotary joint, thus enabling an individual monitoring and control of parameters. Thus the individual drier problems arising due to the heat transfer and differential pressures can be accurately diagnosed and rectified. Further, the temperatures at the individual driers can be set, measured and controlled, which enables the operator to achieve optimal heat transfer rate.

The integrated rotary joint of the present invention can be advantageously used in a broad range of applications that include drying rotary drums of cylinders. Examples of such applications include the rotary cylinders used in textile and pulp & paper industries. It should be noted that the examples given here are illustrative, and they do not restrict the scope of the invention in any way. All such rotating equipment wherein the steam enters a rotary drum and the condensate exists are covered within the scope of the present specification.

The present invention offers one or more of the following advantages:

1. Diagnosis of the inception of drier flooding i.e. through vacuum creator & differential pressure control

2. Seal wear rate detection i.e. alarm on wear of seal (also help to avoid leakage) 3. Steam flow measurement to diagnose individual drier problem with respect to steam consumption

4. Steam pressure measurement to diagnose individual drier problem with respect to

differential pressure

5. Steam temperature measurement to diagnose individual drier problem with respect to heat transfer to drier surface

6. Assisted evacuation using vacuum creator

7. Inbuilt Sight glass provided to observe condensate removal

8. Cantilever siphon design to avoid siphon failure problems

9. This product covers detecting & monitoring Driers of all types in any industy that need

Rotary joints/unions and covers mechanical/electronic and software systems.

In general, the various embodiments of the monitoring system of the present invention may be implemented in hardware or special purpose circuits, software, logic, or any combination thereof. For example, some aspects may be implemented in hardware, while other aspects may be implemented in firmware or software which may be executed by a processor, such as a controller, microprocessor or other computing device, although the invention is not limited thereto.

Thus, the present invention has been described herein with reference to a particular embodiment for a particular application. Although selected embodiments have been illustrated and described in detail, it may be understood that various substitutions and alterations are possible. Those having ordinary skill in the art and access to the present teachings may recognize additional various substitutions and alterations are also possible without departing from the spirit and scope of the present invention, and as defined by the following claims.