MXPA99007006A - Fuel injector nozzle with preheat sheath for reducing thermal shock damage - Google Patents

Abstract

The operating life of a fuel injector nozzle (10) for a gasifier is prolonged by shielding the fuel injector nozzle (10) with a preformed protective insulating sheath (70) before the fuel injector nozzle (10) is installed inside a preheated reaction chamber of the gasifier. The thermal insulating sheath (70) has low thermal conductivity and is placed around the fuel injector nozzle body. The thermal sheath (70) can also be positioned to cover a downstream end (16) of the fuel injector nozzle (10) that includes a nozzle portion (40). The thermal insulating sheath (70) is supported by ceramic rope, solder or metal wire and is gradually consumable in the environs of the reaction chamber immediately after the fuel injector nozzle (10) is installed. Before the thermal sheath (70) is consumed, it moderates the temperature rise rate of the fuel injector nozzle (10) while the fuel injector nozzle (10) is being installed in the gasifier.

Description

NOZZLE FOR FUEL INJECTION WITH A PREHEATING COVER TO REDUCE THERMAL SHOCK DAMAGE BACKGROUND OF THE INVENTION The present invention relates to nozzles for the injection of fuel for gasifiers, and more refers to an apparatus and method to protect the fuel injection nozzles from damage by thermal shock when installing these fuel injection nozzles in a preheated reaction chamber of the gasifier. Generally, the gasification process is carried out by passing oil, gas or a thick carbonaceous aqueous suspension of coal or particulate coke ("carbonaceous matter") and an oxygen-containing gas in the reaction chamber of the gasifier at operating temperatures that can change from approximately 2400 ° F to approximately 3000 ° F. The operating temperature of the gasifier causes the oxygen-containing gas to react rapidly with the carbonaceous matter as it enters the reaction chamber. atomized from the nozzle for the fuel injection of the gasifier into the reaction chamber together with an oxygen-containing gas, since the oxygen-containing gas and the carbonaceous matter have a self-sustained exothermic reaction at operating temperatures typical of the gasifier, nozzle for fuel injection can not have an ignition device. US Pat. No. 4,808,197 to Ayers and Patent 4,443,230 to Stellacio, generally describe the processing of carbonaceous fuels such as coal, in a gasifier to produce gaseous mixtures including hydrogen and carbon monoxide, referred to as synthesis gas. Since the operating temperatures of the gasifier are relatively high, it is occasionally necessary to repair or replace one or more components of the gasifier, such as the nozzle for fuel injection. The gasifier must be stopped and the fuel injection nozzle turned off to allow the gasifier to cool to a temperature that allows for repair or replacement operations as required. Usually, the fuel injection nozzle is constructed as a component that can be removed from the gasifier and removed as needed to facilitate repair of the gasifier structure, as well as cleaning and replacing the nozzle for fuel injection. When the cleaning or repair operation of the gasifier is completed and the operation of the gasifier is restarted, it is typical to increase the temperature of the gasifier reaction chamber to the starting level before restarting the gasification process. The reaction chamber must be preheated to the desired start temperature, such as from about 1600 ° F to about 2400 ° F. Since the fuel injection nozzle can not include an ignition device, it is necessary to preheat the reaction chamber of the gasifier by means of an auxiliary preheating burner operating with an ignition device. Frequently, the known preheating burners use gas as fuel. The preheat burner is installed at one end of the gasifier inlet, so as to allow removal of the preheat burner after the operation of the preheat burner increases the temperature of the reaction chamber to the desired start temperature. The duration of the preheating process depends on the size and mass of the reactor vessel. Once the reaction chamber is preheated to the desired start temperature, the burner is usually removed from the gasifier to allow installation of the nozzle for fuel injection. Generally, before installing the nozzle for the fuel injection in the preheating gasifier, it is relatively cold compared to the starting temperature of the gasifier. With a substantial temperature difference between the pre-installed fuel injection nozzle and the start temperature of the gasifier, the nozzle for fuel injection, after installation, is subjected to a temperature increase to a relatively high average. Different averages of thermally induced physical expansion, due to abrupt temperature changes, can cause a break due to excessive expansion of the nozzle components for fuel injection. Thus, it is almost inevitable that the fuel injection nozzle suffer immediate thermal shock damage when installed in the gasifier. According to its use herein, the phrase "thermal damage" includes damage by thermal shock. Frequently, the thermal damage is manifested by the formation of fissures, for example, around the exit orifice of the nozzle for fuel injection which may include refractory elements. In the same way, these refractory elements develop small cracks that eventually become cracks, which is a rise of chips in the refractory material. In addition, the phenomenon of thermally induced fatigue may occur in the metal structural elements of the nozzle for fuel injection exposed to gasifier environments at high temperatures. The thermal damage of the nozzle for fuel injection during installation is particularly insidious, since the gasification process generates a highly corrosive liquid slag and / or corrosive gases that can penetrate the refractory materials of the nozzle for fuel injection and accelerate the degradation of the nozzle components for fuel injection. Frequently, the utility life of the nozzle for fuel injection is directly related to the amount of thermal damage to which it is subjected during the installation of the nozzle for the injection of fuel into the gasifier. The life of the nozzle for fuel injection is almost always compromised by the initial thermal damage that develops during the installation of the fuel injector. Thus, it is desired to reduce the average nozzle temperature increase for fuel injection and minimize thermal damage to the nozzle for fuel injection when it is cold installed in the gasifier that is already at the start temperature. It is also desired to reduce the thermal damage of the nozzle for fuel injection when it is allowed to warm up to the start temperature and then a carbonaceous and cold oxygen jets are introduced through the nozzle for fuel injection into the chamber of reaction.

OBJECTIVES OF THE INVENTION Among other objectives of the invention can be noted the consideration of a nozzle for the injection of novel fuel for a gasifier, this nozzle for the injection of fuel for a gasifier that incorporates a covering or thermal protection to reduce the average of increase in temperature, a nozzle for the injection of novel fuel for a gasifier that incorporates a thermal cover destructible gradually to allow the eventual exposure of the main structural elements of the nozzle for fuel injection to the environment of the gasifier at averages of increases of temperature gradually, a nozzle for the injection of novel fuel with thermal covering for gasifier that allows the operation of the nozzle for the injection of fuel while the thermal covering of the nozzle for fuel injection dissipates gradually or quickly, and a Novel method to reduce the thermal shock in the nozzle for the fuel injection of a gasifier. Other objects and aspects of the invention will be apparent and described below.

SUMMARY OF THE INVENTION According to the invention, a preformed thermal insulation cover is provided around the outer portions of the fuel injection nozzle that is disposed within the reaction cer of the gasifier. The insulating cover can cover the end of the outlet nozzle or stream below the nozzle for fuel injection and, preferably, is placed in position using safety devices such as for example consumable wires or cables, welding or ceramic tapes. It is also possible to use adhesives to join all or some portions of the thermal insulating cover to the outer body of the nozzle for fuel injection. The thermal cover and all the support devices or adhesives for holding the thermal cover in position in the gasifier are made of materials that are consumed totally or partially in the preheated thermo-chemical environment of the reaction cer of the gasifier. Once the support devices are partially or totally consumed, any portion that has not been consumed from the thermal cover can be blown from the nozzle for fuel injection by a nitrogen purge jet, a jet of carbonaceous feedstock and gas that contains oxygen. The degradation, deterioration and consumption of the thermal cover begins at the time of installation of the nozzle for fuel injection in the gasifier and continues for a predetermined time. When the thermal cover is substantially consumed in the reaction cer, the outer surface of the nozzle for fuel injection is exposed to the thermo-chemical environment of the gasifier. At the time of exposure, the nozzle for fuel injection will have been heated to the modified temperature due to the presence of the thermal insulator cover, thereby minimizing the thermal damage that would otherwise occur in the thermal cover. The reduction of thermal damage in the installation of the nozzle for fuel injection in the gasifier serves to prolong the useful life of the nozzle for fuel injection. Accordingly the invention comprises the construction and the method described above, the scope of the invention is indicated in the claims. DESCRIPTION OF THE DRAWINGS In the accompanying drawings, Figure 1 is a sectional view of a nozzle for fuel injection with a thermal insulating cover incorporated in an embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION Referring to Figure 1, a nozzle for fuel injection of the type presented in US Pat. No. 4,443,230 to Stellacio generally indicated with reference number 10 is described. The fuel injection nozzle 10 is a nozzle for injection of partial oxidation fuel with cylindrical symmetry about the central axis 12. The nozzle for fuel injection 10 includes an upstream end 14 and a downstream end 16. The nozzle for fuel injection 10 further includes a central duct 20 and concentric annular ducts 22, 24 and 26 converging in the form of a nozzle 40 at the downstream end 16. The mounting flange 28 attached to the conduit 26 engages the open end of the gasifier reaction chamber inlet (not shown) and it allows the nozzle 40 to be suspended or hang in the reaction chamber. The conduits 20, 22, 24 and 26 include the respective inlet pipes 30, 32, 34 and 36. The inlet pipe 30 supplies a fuel jet of gaseous combustible material such as, for example, the group of gases containing free oxygen, steam , gas product of recycling and hydrocarbon gas. The inlet pipe 32 supplies a liquid phase suspension which can be pumped out of solid carbonaceous fuel such as, for example, aqueous suspension of cold water. Inlet pipes 34 and 36 provide two fuel separator jets such as gas containing free mixed oxygen, optionally with a temperature moderator. The jets of oxygen-containing gas and the carbonaceous suspension of the conduits 20, 22, 24 and 26 are combined at a predetermined distance beyond the nozzle 40 to a predetermined location in the reaction chamber to form a reaction zone. The combination of the carbonaceous suspension leaving the conduit 22 with oxygen-containing jet from the conduits 20, 24 and 26 causes the carbonaceous suspension to be dispersed or atomized, which promotes the reaction of the product and improves the gasification process induced by the hot. An annular coaxial water cooled jacket 50 is provided at the downstream end 16 of the fuel injection nozzle 10 around the nozzle 40. The cooling jacket 50 receives inlet water 52 through the inlet pipe 54 The water 52 exits from the annular cooling jacket 50 to the 56 in the cooling coil 58 and exits from the cooling coil 58 in any known drainage or recirculation device. When a repair or replacement of the nozzle for fuel injection 10 is required, it is usually necessary to remove the fuel injection nozzle from the reaction chamber (not shown) from the gasifier. Thus, the nozzle for fuel injection 10 is deactivated and allowed to cool before it is removed from the reaction chamber by means of the mounting flange 28. It may also be necessary to remove the nozzle for fuel injection 10 for allow access and repair other structures within the gasifier. When the service or repair of the nozzle for fuel injection 10 and / or any other structures of the gasifier is completed, operation of the same is resumed. Restarting the operation of the gasifier requires raising the temperature in the reaction chamber to the starting temperature of approximately 1600 ° F to 2400 ° F. Since, typically, the fuel injection nozzle does not include an ignition device and is not designed for the start-up operation, another heat source must be used to heat the reaction chamber to the temperature level that can sustain the nozzle operation for fuel injection.

A known preheat burner (not shown) is installed in the gasifier to fulfill this purpose, and is removed when the desired start temperature has been reached. Thus, the nozzle for the fuel injection 10 is installed in the preheated gasifier, when the starting temperature in the reaction chamber has already been reached. The nozzle for fuel injection is relatively cold compared to the temperature in the reaction chamber and is vulnerable to thermal damage when it is first installed in the reaction chamber. The installation of the nozzle for fuel injection 10 in the gasifier is one of the most critical phases of the gasifier operation. When thermal damage that occurs to the fuel injection nozzle 10 during installation will worsen over time due to the high temperature continuous operation of the gasifier and the nozzle for fuel injection. Thus, the thermal damage of the nozzle for the injection of fuel 10 when installed in the gasifier has an adverse effect on the useful life of the nozzle for fuel injection and in the productive operation of the gasifier. Generally, cold water from the nozzle for fuel injection 10 may be passed before starting the installation of the nozzle for fuel injection.

In order to reduce the heat shock damage in the nozzle for the fuel injection 10 in the starting operation of the gasifier, I have developed a flexible, fungible thermal cover 70 arranged to wrap around the periphery of the nozzle for fuel injection 10. before the fuel injection nozzle is installed in the gasifier. The thermal cover 70 can be a preformed insulating protective surface or a constant 1 to 2 inch thick mouldable fiber mixture that surrounds the orifice of the nozzle for fuel injection. Thermal cover 70 can be formed, for example, of ceramic fibers, gypsum, mineral wool, rock slag, granulated slag, diatomaceous earth, or combinations thereof, linked with any desirable known binder such as, for example, inorganic clay, cements, oils or glues. Fiberglass sheets can usually be used as insulation. If desired, electrical heating elements 72 can be provided in the cover 70 or near the inner surface 74 of the cover 70 and placed in place with the ceramic tape, with wire, welded or with a bonding agent for medium temperature or low (not shown). The heaters 72 can be operated prior to the installation of the nozzle for fuel injection 10 in the gasifier.

The cover 70 is clamped around the periphery of the nozzle for fuel injection 10 by a support mechanism 76 such as for example ceramic tape, welding, non-crosslinked steel wire or wires of metal alloys at low temperature, which is they destroy at approximately 2000 ° F and are secured to an anchoring device such as a hook 78 that is placed on the underside of the mounting platform 28 or around the conduit 26, preferably, the support structure 76 or the supporting mechanism it will have a melting point or it will degrade at a set temperature that is lower than the operating temperature of the reaction chamber. As an additional option, the thermal cover 70 can be held in place in the fuel injection nozzle 10 by a wire spring (not shown) which surrounds the exterior of the thermal cover 70 and holds the cover in place. the periphery of the nozzle for fuel injection. The heat cover 70 may have a continuous preformed structure, or a quilt arrangement of preformed small covers. Preferably, the cover 70 covers the nozzle 40 of the nozzle for fuel injection 10. To facilitate the installation of the thermal cover 70 around the nozzle for fuel injection 10, a rigid cover 80 made for example of wood, plastic or sheet metal can be provided for wrapping the cover 70 or securing the cover 70 against the nozzle 40. For example, the cover 80 can be secured to the cover 70 by wires or glue or secure the cover 70 to the mounting platform 28 by means of wire before the installation of the nozzle for fuel injection 10 in the gasifier. Alternatively, a cross-linked structure may be provided, such as in the form of the chicken wire fabric (not shown), around the exposed surface of the thermal cover and fixed to the mounting flange 28, using a anchoring hook 78. If desired, a support of the thermal cover 70 can be made by attaching the inner surface 74 to the outer conduit 26. However, it does not matter what supporting or holding mechanism 76 is used for the cover 70, what is relevant is that the tolerance to the temperature of the support should allow the melting, degradation or any other type of deterioration of the supporting mechanisms 76 at operating temperatures of the reactor in such a way as to allow the cover 70 and any covering material 80 to fall of the nozzle for fuel injection 10 when a jet of matter is introduced into the nozzle for fuel injection.

Nor does the type of thermal cover 70 that is secured around the nozzle for fuel injection 10 matter, an essential feature of the cover 70 being that it undergoes structural failure, decomposition, degradation and / or consumption after a predetermined time in the preheated gasifier. The initiation process that flows through the nozzle for fuel injection, such as a suspension flow can also include the structural failure of the support or retention mechanism 76. During the time when the retention mechanism 76 and the cover 70 are left in place, the nozzle for fuel injection 10 is gradually heated in the reaction chamber to the start temperature, thereby minimizing thermal damage that may otherwise occur from the sudden exposure of the a structure of the nozzle for the injection of fuel before the heating environment of the reaction chamber. Thus, the thermal cover 70 serves to moderate the transfer of heat from the reaction chamber of the gasifier to relatively cool the nozzle for fuel injection 10 after the installation of the nozzle for fuel injection 10 in the gasifier. The degradation and final consumption of the thermal cover 70 in the gasifier due to the operating temperature in the reaction chamber results in that the fuel injection nozzle 10 is eventually exposed directly to the environment of the reaction chamber, but with Initiated process flows that eventually reduce the thermal cycle. However, before there is a direct exposure of the nozzle for fuel injection to the environment of the reaction chamber, the average nozzle temperature increase for fuel injection in the installation with the cover is minimized. thermal and reduces the possibility of causing thermal damage that usually occurs without the thermal cover. Thus, the nozzle for fuel injection. With reduced thermal damage after installation, the operating temperatures of the gasifier reaction chamber can be withstood for an extended period of service due to the thermal damage that will occur when the nozzle for fuel injection is installed in accordance with the present invention. A significant factor that affects the useful life of the nozzle for fuel injection is the thermal damage it suffers during installation. All the constituents of the thermal cover, including the support elements, once they are consumed or fall out of the fuel injection nozzle into the atmosphere of the reaction chamber, do not represent a significant residue or accumulation inside the gasifier. may interfere with the gasification process. Some advantage of the present invention, evident in the above description, is the nozzle for fuel injection with a flexible, consumable, thermal protective cover. The thermal cover controls the average nozzle temperature increase for fuel injection during and after installation in the preheat gasifier. Another advantage of the invention is that the thermal cover minimizes thermal damage when the fuel injection nozzle is installed in the gasifier and thus alleviates the thermal fatigue damage that may occur during the normal operation of the nozzle for fuel injection . Thus, the nozzle for fuel injection with reduced thermal damage during installation has an increase in its useful life. In view of the above, it will be appreciated that several objects of the invention are achieved and other advantageous results are obtained. Since several changes can be made in the constructions and in the method of the invention without departing from its scope, it is intended that the entire object of study contained in the previous description or that is shown in the appended drawings will be interpreted as an illustration and never with intent to limit the invention.

Claims (13)

1. Claims 1. A nozzle for fuel injection for a gasifier comprising: a) a nozzle body for fuel injection having an outer part, an upstream end and a downstream end, the downstream end having the shape of a nozzle portion, b) at least a first conduit extending from the upstream end to the downstream end to allow the flow of the oxygen-containing gas stream from the nozzle portion at the downstream end , c) at least a second conduit extending from the upstream end to the downstream end to allow the flow of a pumpable carbonaceous suspension or gas from the nozzle portion at a downstream end, this second conduit it is placed substantially parallel to the first conduit at the upstream end, and d) a preformed insulating material cover placed From the outside of the nozzle body to the fuel injection between the upstream end and the downstream end, this preformed insulating material is gradually consumed when it is disposed in the environment of the preheated reaction chamber of a gasifier. The fuel injection nozzle for a gasifier according to claim 1, wherein the nozzle for fuel injection includes a mounting platform and the retaining mechanisms provided in the preformed insulating cover to secure the preformed insulating cover on the mounting platform. This retention mechanism is consumed in the environment of the preheated reaction chamber of the gasifier. 3. The nozzle for fuel injection for a gasifier according to claim 2, wherein the retention mechanism is selected from a group consisting of wire cloth for poultry house, ceramic tape, non-crosslinked steel wire and alloys of metal that are destroyed at approximately 2000 ° F. 4. The nozzle for fuel injection for a gasifier according to claim 1, wherein the nozzle stops. The fuel injection includes a mounting platform and a preformed insulation cover that is secured to the mounting platform. 5. The nozzle for fuel injection for a gasifier according to claim 1, wherein electric heaters are provided in the preheating insulator cover to preheat the nozzle body for fuel injection before it is installed in the reaction chamber of the gasifier. The fuel injection nozzle for a gasifier according to claim 5, wherein the preheating insulating cover has an internal surface forming the body of the nozzle for fuel injection and the electric heaters are provided in the internal surface to heat the body of the nozzle for fuel injection before it is installed in the reaction chamber of the gasifier. 7. The fuel injection nozzle for a gasifier according to claim 1, wherein the preformed insulation cover covers a predetermined portion of the exterior part of the nozzle body for fuel injection which is inserted into the reaction chamber of the gasifier. 8. The nozzle for fuel injection for a gasifier according to claim 1, wherein the preformed insulating cover covers the nozzle portion. 9. A method to increase the useful life of the nozzle for the fuel injection of a gasifier comprising, a) preforming the cover of the thermal insulating material that is gradually consumed in the environment of the preheated reaction chamber of a gasifier, b ) placing the preformed thermal insulation cover over the predetermined portions of the fuel injection nozzle to wrap or coat the predetermined portions of the fuel injection nozzle before it is installed in the preheated reaction chamber of the gasifier, c) fasten the thermal cover on the fuel injection nozzle to retain the thermal cover on a nozzle end of the nozzle for fuel injection, and d) install the fuel injection nozzle with a thermal insulating cover on the fuel injection nozzle. the preheated reaction chamber of the gasifier so that the thermal insulation cover is exposed to the environment of the preheated reaction chamber, so that before this thermal cover is consumed, it limits the increase in temperature in the nozzle for the injection of fuel when it is installed in the preheated reaction chamber of the gasifier. The method according to claim 9, wherein the thermal cover is clamped in the nozzle for fuel injection with a cover support that is consumed in the environment of the preheated reaction chamber and the cover of the preheated reaction chamber is placed. Preformed thermal insulation in the nozzle for fuel injection to allow this cover to fall off the nozzle end of the nozzle for fuel injection before the cover support is consumed, as the process begins flow in the nozzle for fuel injection. The method according to claim 9m which includes forming the support for the cover for the preformed thermal insulation of ceramic tape. The method according to claim 9, which includes the formation of a support for the cross-linked wire thermal insulation cover. The method according to claim 9, which includes the formation of the support for the thermal insulation sheath of metal alloy wire at low temperature which is destroyed at approximately 2000 ° F.