GB2046411A

GB2046411A - Condensate booster drainage control system

Info

Publication number: GB2046411A
Application number: GB7914277A
Authority: GB
Original assignee: Crane Ltd
Current assignee: Crane Ltd
Priority date: 1979-04-24
Filing date: 1979-04-24
Publication date: 1980-11-12
Also published as: DE3016137A1; IT1144098B; IT8048475A0; GB2046411B; ZA792901B

Abstract

The invention relates to a condensate booster drainage control system for returning condensate with a high heat content to a boiler or feedwater system so as to improve plant operation and to improve heat transfer rates, the system being of the type having a jet pump 10, a motor-driven centrifugal pump 24, an air separator 44 and vent 46. A valve-controlled start-up air purge line 58 is provided. <IMAGE>

Description

SPECIFICATION Condensate booster drainage control system This invention relates to a condensate booster drainage control system. More specifically, it relates to a system which is designed to return condensate with a high heat content to a boiler or feed-water system so as to improve plant operation and to improve heat transfer rates.

There is already available on the market a condensate booster drainage control system comprising: (a) a jet pump which receives hot condensate and pumps it, in admixture with air and steam, to a motor-driven centrifugal pump capable of handling hot water and providing a sufficient discharge head to activate the jet pump and to provide energy to discharge condensate to a boiler, feedwater system or other appropriate discharge point; (b) a recirculating finned loop which connects the delivery side of the centrifugal pump to the input side of the jet pump, the loop providing a temperature depression to ensure proper venting of the system while maintaining proper suction conditions for the centrifugal pump; (c) an air separator and vent for the automatic discharge of non-condensible gases from the system; and (d) a differential pressure control valve which ensures a diversion of a sufficient quantity of condensate through the finned loop to energize the jet continuously.

The present invention is concerned with an improved form of this condensate booster drainage control system.

According to one aspect of the invention, the system described above incorporates a valvecontrolled start-up air purge line. This permits air and other non-condensible gases to be purged from the system on start-up and, also, if the air vent breaks down, to allow air to be vented from the system during operation of the latter until the defective air vent has been repaired or replaced.

According to another aspect of the invention, the shaft of the centrifugal pump is provided with a thrower in the form of a synthetic plastics disc (preferably of Neoprene) fixed on the shaft so as to throw off water which leaks onto the shaft. As the centrifugal pump casing will generally have windows opposite the thrower, the use of a synthetic plastics material for the thrower will reduce the possibility of accident should anyone put their fingers into the said pump casing through the windows.

The invention is also directed, in another of its aspects, to the provision of guards on a pedestal on which the centrifugal pump and its driving motor are mounted so as to give protection against injury from the coupling between the said pump and motor.

In addition, the invention extends, in yet another one of its aspects, to the provision of flanged connections between various tubular parts in the system in place of the screwed nut connections hitherto used. The latter can seize up with use, whereas flanged connections generally present no problem if it is subsequently desired to disconnect two tubular parts of the system from each other.

By way of example, a specific condensate booster drainage control system in accordance with the invention is shown in the accompanying drawings, in which: Figure 1 is a diagrammatic vertical section through the system; Figure 2 is a front view of the system; Figure 3 is an end view of the system; and Figure 4 is a plan view of the system.

The system shown in the drawings is, in the main, of a design which has been well-tried and extensively used in industry. Accordingly, the system as a whole will be described quite briefly.

As already indicated, the illustrated condensate booster drainage control system is designed to return condensate with a high heat content to a boiler orfeedwater system so as to improve plant operation and to improve heat transfer rates. The system is of very wide application in industry and can be used, for example, with steam corrugators for making corrugated board, jacketed mixers and kettles, platen presses, drying rolls for paper-making machines, dryers for veneer-plywood and wallboard, drying cans for drying textiles, space heaters, ironers and other laundry equipment, and coil cookers.

The system here shown comprises a jet pump 10 having an inlet opening 12 which receives hot condensate from an inlet pipe 14. The jet pump has a venturi tube 16 and a jet nozzle 18 both made as stainless steel inserts which fit into the jet pump casing 20 and an expansion tube 22 respectively.

The jet pump serves to pump the hot condensate, in admixture with air and steam, to a centrifugal pump 24 through a pipe 26. The pump 24 has a shaft 28 which projects through an end opening in its casing 30 and is coupled, by means of a coupling 32, to the shaft 34 of an electric motor 36. The pump 24 is capable of handling hot water and of providing a sufficient discharge head to activate the jet pump 10 and to provide energy for discharging condensate to a boiler, feed-water system or other appropriate discharge point.

A recirculating inverted-U pipe or loop 38 having fins 40 connects the delivery side of the centrifugal pump 24 to the input side of the jet pump 10. The loop provides a temperature depression to ensure proper venting of the system while maintaining proper suction conditions for the centrifugal pump 24. A branch-pipe 42 from the loop 38 leads to an air separator 44 on which is mounted an air eliminator 46 having an air vent 48 for the automatic discharge to atmosphere of non-condensible gases from the system, the air separator 44 having an outlet pipe 50 leading to the air eliminator 46. A further outlet pipe 52 from the air separator 44 leads to a differential pressure control valve 54 which ensures a diversion of a sufficient quantity of condensate through the finned loop 38 to energize the jet nozzle 18 continuously.The valve 54 has a discharge side 56 which is connected to a boiler or other receiver.

When used with a boiler or other steamgenerating plant, the above-described system is able to reduce steam costs to a substantial extent. The centrifugal pump 24 is able to return condensate to the boiler or feedwater system at a temperature only marginally below that at which it is condensed. This means that flashed steam losses are greatly reduced or are eliminated. There is also a more complete transfer or available latent heat to the condensate leaving the system. Furthermore, there is an improved transfer of heat in the system arising from the continuous controlled purging of condensate, gases and air, and from the positive automatic regulation of the vent rate to maintain a minimum pressure drop across the vent 48.

The above-described features of the illustrated system are already known from the condensate booster drainage control systems available on the market. The distinctive novel features proposed by the present invention will now be described.

It is frequently found, when the system is started up, that there is already an unacceptable amount of air contained in the various parts of the system.

Accordingly, the present invention makes provision for the inclusion in the system of a start-up air purge line 58 branching off the air outlet pipe 50 which leads from the air separator 44 to the air eliminator 46. The start-up air purge line 58 is controlled by a hand-operated valve 60. When the system is started up, a hand-operated valve 62 in the pipe 50 is closed and the valve 60 is opened to purge air from the system. Thereafter the valve 60 is closed and the valve 62 opened to allow venting in the normal way through the air vent 48.

Provision of the air purge line 58 and its valve 60 permits air or other non-condensible gases to be purged from the system not only on starting-up of the system but also if the air vent 48 breaks down. In other words, a break-down of the air vent 48 does not put the whole system out of action, as it can continue to operate with the valve 62 closed and with the valve 60 opened so that the purge line 58 takes the place of the air vent 48. This can continue until the defective air vent has been repaired or replaced.

It will be seen from Figure 1 thatthe shaft 28 of the centrifugal pump 24 passes through a water-cooled stuffing box 64. In order to prevent water leaking along the shaft, a thrower in the form of a synthetic plastics disc 66 is fixed on the shaft so as to throw off water which leaks on to it. Although many synthetic plastics materials can be used for the disc, it is preferably made of Neoprene. It is usual to provide the centrifugal pump casing 30 with windows or openings opposite the thrower 66 so that the use of a synthetic plastics material for the latter reduces the possibility of accident should an engineer put his fingers into the said pump casing 30 through the windows.

The coupling 32 between the centrifugal pump shaft 28 and the shaft 34 of the motor 36 driving it can be a hazard if unprotected. Accordingly, guards 68 are provided on a pedestal 70 on which the centrifugal pump 24 and its motor 36 are mounted so as to give protection against injury from the coupling.

It will be seen from all the drawings that the system is built up from various parts which are connected together in a fluid-tight manner. Hitherto the connections have been screwed together. Such screwed connections can, however, seize up after a prolonged period of use and can therefore be very difficult to disconnect when the time comes for inspection or repair of the system. Accordingly, the connections in the system illustrated in the accompanying drawings take the form of flanges which are connected together by screws or bolts which are well clear of the fluid passing through the system.

Thus, the connections 72,74,76,78,80 and 82 all comprise a pair of flanges which are connected together by bolts or screws 84, there being a fluid-tight sealing ring 86 between each pair of abutting flanges.

Combined with the use of the Neoprene thrower 66 on the shaft 28, an additional safety feature is the provision offurtherwire-mesh guards 88 adjacent the windows or openings in the pump casing 30 opposite the thrower 66.

It will thus be seen that the invention introduces significant improvements into the form of system hitherto used and that these means bring definite practical advantages.

Claims

1. A condensate booster drainage control system for returning condensate to a boiler or feed-water system, the control system comprising a jet pump serving to receive hot condensate, a motor-driven centrifugal pump connected to the jet pump so as to receive hot condensate therefrom in admixture with air and steam and to discharge condensate to a boiler or feedwater system, and an air separator and vent for the automatic discharge of non-condensible gases from the system, in which a start-up air purge pipe or passage controlled by a valve is included in the control system.

2. A condensate booster drainage control system according to claim 1, in which the start-up air purge pipe or passage branches off from an air outlet pipe leading from the air separator to an air eliminator.

3. A condensate booster drainage control system according to claim 1 or claim 2, in which the valve is controlled by hand.

4. A condensate booster drainage control system according to any one of claims 1-3, in which a thrower in the form of a synthetic plastics disc is fixed on the shaft of the centrifugal pump so as to throw off water which leaks onto the shaft.

5. A condensate booster drainage control system according to any one of claims 1-4, in which one or more guards are fixed to a pedestal on which the centrifugal pump and its driving motor are mounted so as to give protection against injury from a coupling between the pump shaft and the motor shaft.

6. A condensate booster drainage control system according to any one of claims 1-5, in which a plurality of flanged connections are provided between various tubular parts of the system to facilitate the disconnection of adjoining tubular parts of the system from each other, there being a fluid-tight sealing ring between each pair of abutting flanges.

7. A condensate booster drainage control system according to any preceding claim, in which the centrifugal pump is adapted to provide, n operation, a sufficient discharge head to activate the jet pump and to provide energy to discharge condensate to the boiler orfeedwater system.

8. A condensate booster drainage control system according to any preceding claim having a recirculating finned loop which connects the delivery side of the centrifugal pump to the input side of the jet pump, the loop providing a temperature depression to ensure proper venting of the system while maintaining proper suction conditions for the centrifugal pump.

9. A condensate booster drainage control system according to claim 8 having a differential pressure control valve to ensure a diversion of a sufficient quantity of condensate through the finned loop to energize the jet continuously.

10. A condensate booster drainage control system for returning condensate to a boiler or feedwater system substantially as described herein with reference to the accompanying drawings.