EMERGENCY COOLING-WATER VACUUM SYSTEM AND METHOD

Abstract

An emergency cooling-water vacuum system and associated method for a pressurized water cooled furnace having an emergency shut off preventing pressurized cooling fluid from moving to the cooling components in the furnace, said system including at least one vacuum inducing unit, a diversion inlet line of pressurized cooling fluid to the vacuum inducing unit configured to be open when the emergency shut off is activated to prevent pressurized cooling fluid from moving to the cooling components in the furnace; and a vacuum line extending from the cooling components in the furnace to the at least one vacuum inducing unit, wherein a vacuum is induced in the vacuum line when pressurized cooling fluid is directed through the at least one vacuum inducing unit.

Claims

1. An emergency cooling-water vacuum system for a pressurized water cooled furnace having an emergency shut off preventing pressurized cooling fluid from moving to the cooling components in the furnace, said system comprising: at least one vacuum inducing unit; a diversion inlet line of pressurized cooling fluid to the at least one vacuum inducing unit configured to be open when the emergency shut off is activated to prevent pressurized cooling fluid from moving to the cooling components in the furnace; and a vacuum line extending from the cooling components in the furnace to the at least one vacuum inducing unit, wherein a vacuum is induced in the vacuum line when pressurized cooling fluid is directed through the at least one vacuum inducing unit.

2. The emergency cooling-water vacuum system for a pressurized water cooled furnace according to claim 1 further including a plurality of vacuum inducing units.

3. The emergency cooling-water vacuum system for a pressurized water cooled furnace according to claim 2 wherein the plurality of vacuum inducing units are mounted in parallel.

4. The emergency cooling-water vacuum system for a pressurized water cooled furnace according to claim 3 wherein each vacuum inducing unit is an eductor.

5. The emergency cooling-water vacuum system for a pressurized water cooled furnace according to claim 1 wherein the at least one vacuum inducing unit includes an eductor.

6. The emergency cooling-water vacuum system for a pressurized water cooled furnace according to claim 5 wherein the system further includes a return line following the at least one vacuum inducing unit and extending to a water outlet line downstream of the furnace to return cooling fluid to a source of cooling fluid.

7. The emergency cooling-water vacuum system for a pressurized water cooled furnace according to claim 6 wherein the system further includes a second emergency stop valve in the water outlet line downstream of the furnace and the vacuum line and upstream of return line.

8. The emergency cooling-water vacuum system for a pressurized water cooled furnace according to claim 7 further including at least one flow valve configured to adjust the vacuum in the vacuum line.

9. The emergency cooling-water vacuum system for a pressurized water cooled furnace according to claim 8 wherein Each eductor has an injector chamber with a narrow shaped nozzle located inside the chamber and which points axially towards an exhaust chamber to increase the pressure of the motive fluid as it enters the eductor.

10. The emergency cooling-water vacuum system for a pressurized water cooled furnace according to claim 9 wherein at a bottom of the nozzle of each eductor is an opening to which the vacuum line is coupled and is used to suck in standing water from the furnace in a cooling fluid shut-off condition.

11. A method of emergency cooling water shut off in a pressurized water cooled furnace preventing pressurized cooling fluid from moving to the cooling components in the furnace, said method comprising the steps of: Opening a diversion inlet line of pressurized cooling fluid when the emergency shut off is activated to prevent pressurized cooling fluid from moving to the cooling components in the furnace; Directing pressurized cooling fluid from the diversion inlet line through at least one vacuum inducing unit; and Inducing a vacuum in a vacuum line extending from the cooling components in the furnace to the at least one vacuum inducing unit.

12. The method of emergency cooling water shut off according to claim 11 wherein the step of directing pressurized cooling fluid from the diversion inlet line through at least one vacuum inducing unit includes directing pressurized cooling fluid from the diversion inlet line through a plurality of vacuum inducing units.

13. The method of emergency cooling water shut off according to claim 12 wherein the plurality of vacuum inducing units are mounted in parallel.

14. The method of emergency cooling water shut off according to claim 13 wherein each vacuum inducing unit is an eductor.

15. The method of emergency cooling water shut off according to claim 11 wherein the at least one vacuum inducing unit includes an eductor.

16. The method of emergency cooling water shut off according to claim 15 further including the step of returning the cooling fluid to a source of cooling fluid after passing through the eductor.

17. The method of emergency cooling water shut off according to claim 16 further including the step of closing a second emergency stop valve in a water outlet line downstream of the furnace and a vacuum line and upstream of a return line.

18. The method of emergency cooling water shut off according to claim 17 further including adjusting the vacuum in the vacuum line.

19. The method of emergency cooling water shut off according to claim 18 wherein Each eductor has an injector chamber with a narrow shaped nozzle located inside the chamber and which points axially towards an exhaust chamber to increase the pressure of the motive fluid as it enters the eductor.

20. The method of emergency cooling water shut off according to claim 19 wherein at a bottom of the nozzle of each eductor is an opening to which the vacuum line is coupled and is used to suck in standing water from the furnace in a cooling fluid shut-off condition.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0034] FIG. 1 is a schematic view of an emergency cooling-water vacuum system according to one embodiment of the present invention.

[0035] FIG. 2 is a schematic view of an emergency cooling-water vacuum system according to a second embodiment of the present invention.

BRIEF DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0036] The present invention provides an emergency cooling-water vacuum system 100 for a water cooled furnace 10 and associated method that acts to minimize the chance of explosion in water cooled furnaces as well as to minimize downtime during repair of the water cooled furnace 10 with two embodiments of this system 100 shown in schematically in FIGS. 1 and 2.

[0037] The system 100 is shown in FIGS. 1 and 2 implemented with an EAF 10, but can be implemented in any water cooled furnace arrangement in which steam explosion minimization and repair facilitation is desired. A full understanding of the existing water cooled system and the emergency stopping of water supply for the EAF 10 will better explain the system 100 of the present invention. The system 100 as shown allows for easy retrofitting of an existing EAF 10 to incorporate the system 100.

[0038] An existing water cooled EAF 10 includes a water inlet line 12 from a source of cooling water (not shown) as well as an emergency shut off valve 14 upstream of the EAF 10. When a water leak is detected in the EAF 10 without system 100 installed the shut off valve 14 is turned off and cooling water is prevented from flowing to the EAF 10. The valve 14, and a pump from the source of cooling fluid, will be controlled by control unit accessed in a control room by the operators, although the emergency shut off may also have one, or more, activation buttons outside of the control room that are easily assessable by workers.

[0039] The inlet 12 divides into separate EAF 10 cooling components, which are shown as an EAF top cooling structure 16, a sidewall cooling structure 18 and an off gas system cooling structure 20. The structures of the cooling shells or jackets forming the top cooling structure 16, the sidewall cooling structure 18 and the off gas system cooling structure 20 are generally known in the art.

[0040] When there is a leak in one of these areas, it is these elements (the EAF top cooling structure 16, the sidewall cooling structure 18 and the off gas system cooling structure 20) that must be repaired before the EAF 10 goes back into operation after a shutdown. Such a repair generally requires welding. Often in this repair, one or more welds must be performed upside down in the area of the leak, and this orientation for the weld can make the process of welding more difficult.

[0041] The existing water cooled EAF 10 includes a water outlet line 22 collecting water from each of the EAF top cooling structure 16, the sidewall cooling structure 18 and the off gas system cooling structure 20. The water outlet line 22 extends to, and returns, the water to the source of cooling water (not shown).

[0042] The emergency cooling-water vacuum system 100 for a water cooled furnace 10 is easily added onto existing EAFs 10 and will include a system inlet line 112, with a reducer 114, extending from the inlet line 12 before, or upstream of, the emergency shut off valve 14. The system inlet line 112 flows to an inlet on/off valve 116 and one way check valve 118. The valve 116 is closed in normal operation (when the shut off valve 14 is open) and will open simultaneously with the closing of the emergency shut off 14. The one way check valve 118 forces flow in the system inlet line 112 in one direction and prevents back flow.

[0043] In one embodiment of the invention shown in FIG. 1, after the inlet on/off valve 116 and one way check valve 118, the system inlet line 112 flows through a flow control valve 120 that variably controls the flow of the high pressure water through the system 100. The flow control valve 120 can be viewed in the embodiment of FIG. 1 as a control over the vacuum created in the system 100. Alternatively, a vacuum line flow control valve 141 may be provided as discussed below. Where a plurality of eductors 122 are used in parallel as shown in FIG. 2, after the inlet on/off valve 116 and one way check valve 118, the system inlet line 112 flows through a header to equally divide the flow into each of the eductors 122.

[0044] The key aspect of the system 100 is flow of the high pressure cooling fluid from system inlet line 112, also called a diversion line, through at least one eductor 122, which is a water powered vacuum creating device. A system 100 with one eductor 122 is shown in FIG. 1 and a system 100 with a plurality, namely a bank of three, eductors 122 mounted in parallel is shown in FIG. 2.

[0045] Each eductor 122 a kind of jet-type pump that does not require any moving parts to be able to pump out or suction out standing water in the top cooling structure 16, sidewall cooling structure 18 and off gas system cooling structure 20 of the EAF 10 when in emergency operation. Each eductor 122 make use of its structure to transfer energy from one fluid to another via the Venturi effect.

[0046] The Venturi effect is the reduction in fluid pressure that results when a fluid flows through a constricted section (or choke) of a pipe. The Venturi effect is named after its discoverer, the 18th century Italian physicist, Giovanni Battista Venturi. In inviscid fluid dynamics, an incompressible fluid's velocity must increase as it passes through a constriction in accord with the principle of mass continuity, while its static pressure must decrease in accord with the principle of conservation of mechanical energy (Bernoulli's principle). Thus, any gain in kinetic energy a fluid may attain by its increased velocity through a constriction is balanced by a drop in pressure. This pressure drop creates the vacuum in the present system for the vacuum line 130.

[0047] Following the eductor 122, or bank of eductors 122 in the embodiment of FIG. 2, a return line 124 extends to the water outlet line 22 downstream of the EAF 10 to return cooling fluid to the source of cooling fluid. A one way check valve 126 in line 124 prevents backflow in line 124.

[0048] The system 100 includes a second emergency stop valve 128 added into the water outlet line 22 downstream of the EAF 10, downstream of a vacuum line 130 coupled to the line 22 and upstream of the connection of the line 124 and line 22. The valve 128 operates simultaneously with the valve 14 and is open in normal operation and closed in emergency operation. The second emergency stop valve 128 essentially prevents the vacuum line 130 from pulling fluid from downstream during operation.

[0049] The system 100 includes the vacuum line 130 coupled to the line 22 downstream of the EAF 10 and upstream of the second stop valve 128. The vacuum line 130 may include a reducer 132.

[0050] The vacuum line 130 flows to a one way check valve 136 and an on/off valve 138. The valve 138 is closed in normal operation (when the shut off valve 14 is open) and will open simultaneously with the closing of the emergency shut off 14. The one way check valve 136 forces flow in system vacuum line 130 in one direction and prevents back flow.

[0051] The system 100 in FIG. 1 includes a gauge 134 to measure the strength of the vacuum created in line 130 which can be adjusted via the control of the flow via valve 120. The system 100 in FIG. 2 has the vacuum line 130 truncate into a header to distribute the flow across the bank of eductors 122. The system 100 in FIG. 2 includes a vacuum line flow control valve 141 for each eductor 122 and includes a gauge 134 to measure the strength of the vacuum created in that portion of the line 130 with the associated eductor 122 and which can be adjusted via the control of the flow via valve 141. The separately controllable bank of eductors 122 and separate vacuum flow control 141 yields some redundancy and greater flexibility to the system of FIG. 2. In operation it is possible that only some of the eductors 122 of the bank of eductors 122 will be utilized, and those that are used may be operated at different flows in some applications.

[0052] The elements of the system 100 can be housed within a housing 140, other than the lines 112, 124 and 130, reducers 114 and 132 and the shutoff 128. In adding to existing furnace applications, also called retrofitting, essentially the housing 140 is mounted in a suitable location generally near the furnace and the lines 112, 124 and 130, reducers 114 and 132 and the shutoff 128 added to add (or retrofit) the system 100 into the existing EAF 10 (or other water cooled furnace)

[0053] Each of the eductors 122 has an injector chamber with a narrow shaped nozzle, or tapered jet, which is located inside the chamber and points axially towards the exhaust chamber to increase the pressure of the motive fluid as it enters the eductor 122. At the bottom of this nozzle is an opening to which line 130 is coupled and is used to suck in standing water from the EAF 10 in the cooling fluid shut-off condition. The suction in line 130 happens due to the Venturi effect that creates a drop in pressure at the tip of the nozzle of eductor 122 due to the fast flowing motive fluid which has gained kinetic energy due to the tapered shape of the nozzle. This difference in pressure causes the desired fluid in line 130 to be sucked into the eductor 122, or bank of eductors 122, and mixed into the flow stream to be guided out of the associated eductor 122 in line 124.

[0054] The eductors 122 are well suited to be used in this application and can minimize the chance of explosions, both due to the elimination of standing water and the prevention of the vacuum creation from being exposed to standard electric or internal combustion powered pumps. After the motive fluid from line 112 has been mixed with the substance from line 130, the shape inside the associated eductor 122 get narrow once again just before the exhaust hole. This narrow shape causes the kinetic energy of the fluid to drop while causing a change in the pressure. This causes a continuous motion of suction of the fluid to be extracted into the eductor 122. This is known as the Venturi effect and it is responsible for the operation of this device.

[0055] The operation of the system 100 of the present invention will be automatic and generally based upon the emergency shut off operation or detection. Operators in the control room may control the vacuum pressure via the valves 120 or 141 to control the vacuum provided. For example there may be some desire to vary the vacuum created by the system 100 during the repair procedure to assist in welding.

[0056] In summary, many hot metal/steelmaking/metal processing furnaces, such as the EAF 10, have pressurized water circuit cooling portions. In the event of a water leak, explosions are possible with existing systems. The system 100 of the present invention can minimize the chance of explosion and facilitate repair of the furnace.

[0057] In operation when a leak is detected the valve 14 is closed in a conventional fashion by the controller. With the system 100 in place the valve 128 will also close simultaneously and valves 116 and 138 of the system will open simultaneously, and the system 100 will automatically divert the cooling water from its usual flow pattern into the vacuum inducing device of the eductor 122, or bank of eductors 122, in order to put the entire downstream cooling section of the water system (e.g., the top cooling structure 16, the sidewall cooling structure 18 and the off gas system cooling structure 20 of the EAF 10) into vacuum and prevent additional water from coming in contact with the liquid steel. The vacuum will draw off standing water from the downstream side namely the top cooling structure 16, the sidewall cooling structure 18 and the off gas system cooling structure 20 of the EAF 10. The vacuum is adjustable via valve 120, or via valves 141 where a bank of eductors 121 is implemented. The risk of explosions is minimized both because of the active withdrawal of water from the EAF 10 as well as the system 100 not introducing unnecessary sparks.

[0058] Further, the repairs of the EAF 10 are enhanced through the minimization of standing water. The vacuum provided by the system 100 can also greatly assist the welding process in the repair of the relevant components of the EAF 10, essentially the operating system 100 can act to pull the welds into the piping which is particularly helpful if welding upside down. The system 100 improves the repair process of the EAF 10 by reducing the repair time and also improving the quality of the repair.

[0059] The system 100 will reduce the damage to the furnace 10 when a water leak is detected and minimize downtime with little added cost or complexity to the overall facility. With the system 100 in shut down mode, existing cooling water is redirected to one or more one-piece pumps to create suction on the static cooling water in the furnace. It is extremely easy to add this system 100 onto an existing furnace 10 by merely connecting via simple piping the emergency stop valves and return lines with the system 100.

[0060] The system 100 is described in connection with EAF 10 for steelmaking, but is not intended to be limited thereto. The background of the invention notes that water cooled EAF furnaces are used in other industries, like some chemical production applications. Another water cooled furnace application is addressing water cooled ducts above an oxygen furnace in the steel making field.

[0061] For another example consider the titanium industry. The titanium industry dates back to the turn of the century, although commercial production of the metal actually started in about 1950. By the end of the twentieth century, the industry was producing more than 100 million pounds per year. Early on, safety problems arose from a lack of knowledge regarding furnace design and related explosions. There have been at least 50 documented VAR furnace explosions in the US titanium industry, the knowledge at the time was based on steel technology, and the hydrogen explosions were a completely new problem. When molten titanium reacts with water, the titanium metal breaks down the water, absorbing the oxygen and liberating the hydrogen, which results in a major explosion. During the first five years of the industry, furnace explosions killed six employees. The very nature of melting titanium in a water-cooled furnace using copper crucibles establishes a risk. Water leaks can occur, and as in the steel making process when water contacts molten titanium, the water turns to steam. However adding to the mix, Titanium has such an affinity for oxygen that it breaks down the water, absorbs the oxygen, and liberates the hydrogen. Under these circumstances, both steam and hydrogen explosions are possible. The system 100 with eductors 122 (having no moving parts or electric components) of the present invention minimizes the chances of igniting a hydrogen explosion when operating thus making the system 100 particularly well suited for this application.

[0062] The above invention may be described as an emergency cooling-water vacuum system 100 for a pressurized water cooled furnace, such as EAF 10, having an emergency shut off 14 preventing pressurized cooling fluid from moving to the cooling components (16, 18 and 20) in the furnace 10, said system 100 comprising: a diversion inlet line 112 of pressurized cooling fluid to at least one vacuum inducing unit 122 configured to be open when the emergency shut 14 off is activated to prevent pressurized cooling fluid from moving to the cooling components (16, 18 and 20) in the furnace 10; and a vacuum line 130 extending from the cooling components (16, 18 and 20) in the furnace 10 to the at least one vacuum inducing unit 122, wherein a vacuum is induced in the vacuum line 130 when pressurized cooling fluid is directed through the at least one vacuum inducing unit 122.

[0063] The above description is representative of the present invention but not restrictive thereof. The full scope of the present invention are set forth in the appended claims and equivalents thereto.