DE3523610A1 - Cooled screen as internal lining for the reaction spaces of furnace installations - Google Patents

Abstract

The invention relates to a cooling screen as the internal lining for highly thermally stressed reaction spaces of for example furnace installations or gas generators for pressure gasification of ash-containing fuels. The cooling screen consists of a cooled outer jacket with pins or pegs fastened thereon and of an internal layer made of a refractory monolithic lining material, in which the inwardly projecting ends of the pins or pegs are embedded. To intensify the cooling effect and to improve the operational reliability of such a reactor, the cooled jacket is, according to the invention, delimited by two plane metal sheets (1, 2) and/or pipe lengths (3, 4 or 5, 6) which are arranged at a predetermined intermediate spacing and which are interconnected by continuous support bolts (7), the free inner end sections of which are embedded in the monolithic lining material. To improve further the desired effects, there can be fastened in a gastight manner in the inner metal sheets (1) and/or the inner pipe lengths (3, 5) additional pins (8), the inner end sections of which are likewise embedded in the monolithic lining material and the outer sections of which project into the continuous cooling space between the metal sheets or pipe lengths, which is flowed through by the coolant. …<IMAGE>…

Description

1. Fuel Institute Freiberg GDR - 92oo Freiberg

2. Gosudarstvenny Nauchno-Issledovatelsky I Proektny Institut Azotnoi Promyshlennosti I Produktov Organicheskogo Sinteza

Moscow - USSR

Cooled screen as inner lining for the reaction rooms of combustion systems

The invention relates to a cooled screen as an inner lining for those with high thermal loads Combustion or reaction chambers of furnaces, gas generators, etc., and can be used in the chemical Industry, especially in gas generators with liquid slag removal and relatively large hydrogen sulfide held in the generator gas.

From DE-OS 2 555 466 (Kl. ClOJ 3/76, 3/86; 1977) is. A cooling screen or an inner lining known for a gas generator with liquid slag discharge, which has a cooling surface formed from pipes. The pipes are gas-tight welded to each other via gas-tight webs and the pipe walls are with clad in a ceramic material applied by plasma or flame. Above it is located a covering mass, which is attached to the pontoons by a

751-U66 957 4) -Sd-E

welded wire mesh is held. This well-known Lining has major disadvantages. The ceramic The ceiling is detached from the pipe walls and the decking area falls together with the ceramic material into the molten slag. There are gas gaps between the water-cooled pipes and the ceramic ceiling, which impair the intensive heat transfer and thus the desired and necessary cooling. The wire mesh can melt, which leads to large-scale outbreaks of the refractory material on the reactor walls and especially in the area of the reactor ceiling.

After the SU inventor's certificate 270 948, there is another one Cooling screen of the specified type for a furnace with central discharge of the molten liquid Prior art slag, in which a cooling jacket is formed from tubes which are connected via webs are welded together gas-tight. Pins are welded to the pipe surfaces and a refractory ramming mass located above and between the pins. This pinned cooling screen also has a practically too low value Operational reliability and service life when used in a plant for pulverized coal gasification Liquid slag removal because of the very high specific heat flows and the high hydrogen sulfide concentrations attack the wall structure in the gases generated. The one welded to the cooled pipe surface Pins conduct the heat absorbed through their end face and their side faces only through the welding point

into the respective cooling pipe. However, these welds have increased thermal resistance. Furthermore, since the length of the pins cannot fall below certain limit values, which are specified by the clamping of the pins in the welding machine and / or by other welding conditions, and also because the proportion of the inner surface of the generator room to be cooled that is allocated to the pins is very limited is, the intensity of the heat dissipation from the combustion chamber surface to be cooled remains relatively small. These circumstances can lead to overheating of the pin free ends, resulting in excessive H ₂ S corrosion and melting of the pin free ends. The heat flow to the pipe surface increases, so that the pipes are overheated and fail. Furthermore, there are excessive heat loads on individual or less special tubes compared to the other cooling tubes, which, in particular if the pins are weakened by melting or corrosion, leads to the cooling water boiling in the tube or to a surge of a steam-water emulsion used as a coolant. The resistance of these pipes increases and the coolant supply is correspondingly reduced or even interrupted. The vapor bubbles that form in the pipe can fill the entire cross-section of the pipe and clog the pipe concerned. The cooling effect and the heat dissipation in the coolant are severely restricted and the pipe burns through.

The invention is based on the object, while avoiding the disadvantages of the prior art, the operational reliability and service life of a combustion system od. like. with partial oxidation of fuels under pressure,

in particular of gas generators with partial oxidation of fuels under pressure and with h < generated generator gas to boost.

Fuels under pressure and with a high H-S content in the

In the case of a pinned cooling screen that has cooling channels and pins as well as a refractory ramming compound, this object is achieved according to the invention in that the cooling channels or spaces through which coolant flows are limited by two metal sheets or two axially parallel pipe sections, which are connected to each other by continuous Support bolts are connected, with additional pins provided in the respective inner sheets and / or Rohxschüsse which protrude into the cooling space delimited by the metal sheets and / or pipe sections.

With such a design of cooling screens, the better operational reliability and results longer service life by equalizing and intensifying the heat transfer to the coolant. The continuous cooling spaces delimited by the metal sheets or pipe sections effectively prevent this from happening Clogging caused by the formation of steam, because the vapor bubbles that may form in the coolant can rise. The through the two sheets or pipe sections through-going support bolts and the additional pins on the respective inner sheets or pipe sections cause a destruction of the possibly forming larger vapor bubbles and prevent their formation steam plugs and overheating of the inner sheets or pipe sections. As the additional pins extend through the inner walls and across protrude into the respective cold room, a

much more intense direct heat transfer to the coolant that preferably flows across it. Another Intensification also results from the increased heat transfer area of each support bolt and pin.

The table shows the cooling surfaces with the same degree of pinning of approx. 25% for one made of coiled tubing built-up cooling screen as well as for one formed from sheet metal and / or pipe sections with a spacing of about 30 mm Cooling screen indicated, the pin diameter in each case being 10 mm.

Tabel

Coiled tubing cooling screen

Cooling shield made of equidistant sheet metal or pipe sections

Cooling surface of the pin mm ²

Area allotted to one pen, mm ²

Total cooling area, mm ²

312.5 312.5

942

234 1176

Finally, there is a significant reduction in thermal resistance during heat transfer by conduction along the pin and on to the coolant in that the majority of the heat, and although more than 80% is transferred directly from the pen to the coolant and only a small part of the heat is transferred via

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the weld between the peripheral surface of the pin and the wall of the sheet metal or pipe section is transferred to the cooling medium.

The use of the support bolts, which pass through the inner sheet metal or the inner pipe section, enables the effective length of the pins protruding on the side of the reaction space to be increased. This length can be chosen depending on the start of the strong hydrogen sulfide corrosion at approx. 350 to 400 ^° C. in such a way that a corresponding service life of the pins is guaranteed.

A preferred embodiment of the invention is shown in the drawing and will be described in more detail below described. Show it:

Fig. 1 shows a cooled inner jacket or

a cooling screen of a gas generator in longitudinal section;

2 shows a section of the cooling screen on an enlarged scale.

The illustrated pinned cooling screen according to FIG. 1 forms the lining construction of a shaft-shaped Reactor, as it is for. B. for the production of generator gas and / or for the pressure gasification of coal dust and others Ash-containing fuels with relatively high sulfur contents are used. The cooling shield includes a double-flow through which a coolant flows continuously

jacket, which is in the form of two equidistantly arranged metal sheets 1, 2 in the cover area of cylindrical pipe sections 3, 4 and adjoining conical pipe sections 5, 6 is executed. The one from each other equally spaced sheets 1, 2 or the pipe sections 3, 5; 4, 6 are each under each other through both through support pins 7 connected and held at the predetermined distance. The inner sheet 1 in the cover part and the inner pipe sections 3, 5 are provided with additional shorter pins 8, whose Ends in the coolant space between the sheets 1 and 2 or between the pipe sections 3 and 4 and 5 and 6 protrude. The support pins 7 and the pins 8 are on the metal sheets 1, 2 and on the pipe sections 3 to 6 Welded on via circumferential weld seams 9, as is particularly shown in FIG. 2.

At the lower retracted end part of the reactor, a ring collector 10 is provided, in which the over a nozzle 11 discharging therein, supplied coolant evenly distributed over the entire circumference and which is in free flow connection with the coolant space between the pipe sections. Another Ring collector 12 with a drain connection for the Coolant (water or steam-water emulsion) is on provided upper end part of the reactor and also communicates with the limited by the pipe sections Cold rooms. The cover part formed from the flat metal sheets 1 and 2 is inserted into the opening of the ring collector 12 installed and has a central opening for a burner 14. This cover part has its own Ring collector 15 with connecting piece 16 for the cooling

medium supply and a further ring collector 17 with a water drainage connection 18, the ring collector 15, 17 are arranged on the radial inner edge or outer edge of the metal sheets 1, 2.

The support bolts 7 and the pins 8 protrude to a suitable length of, for. B. 8 to 15 mm over the inside Sheet metal 1 or the inner pipe sections 3, 5 to the side of the reaction chamber out. On these free ones End portions of the support pins and pins, the refractory ramming mass 19 is in a predetermined Layer thickness attached. The support bolts not only have the task of defining the ramming mass and the heat dissipation, but they also form stiffening and supporting elements, which the Area 1, 2 and the pipe sections 3, 4 or 5, 6 to form a rigid structural unit connect, which allows working with high pressure.

A cooling screen designed according to the invention works as follows:

The ring collectors 10 and 15 are supplied with water or another suitable coolant via the nozzles 11, 16 fed in a continuous stream, which in the sheets 1 and 2 or the pipe sections 3, 4 and 5, 6 limited cold rooms flows through it and thereby the Carrying bolts 7 and the protruding pins 8 washed around intensively. The heated coolant is in the ring collectors 12 and 17 collected and discharged via the connection 13 and 18, respectively.

The salt-containing fuel passes through the burner 14 into the reaction space delimited by the cooling screen (Coal dust) and the oxygen-containing gas, e.g. B. a mixture of technical oxygen and water vapor . The temperature in the reaction space is above the temperature of normal liquid slag removal held, wherein the ash particles contained in the fuel are melted and at least partially on the inner surface of the ramming mass 19 cooled by the support bolts 7 and the pins 8. At this A layer of slag, usually 1.5 to 3 mm thick, is formed on the inner surface of the ramming mass 19 which flows off the impinging liquid slag without coming into contact with the ramming mass 19, so that this cannot be resolved either. The draining slag melt collects in the lower part of the Reaction chamber and is installed within the ring collector 10 by a - not shown Slag drain body discharged. The heat dissipated via the support bolts 7 and the pins 8 the ramming mass 19 is given off to the circulating cooling water, which is heated in the process and when designed of the cooling screen to cooling with steam-water emulsion can begin to boil. The hot water or the steam-water emulsion is in the ring collectors 12 and 17 collected and discharged through the connection 13 and 18, respectively.

The inventive cooling shield allows an increase in the temperature in the reaction ^{zone of a gas generator by 300 to 500 0} C and at the same time a restriction of the maximum temperature of the BoI-

zen or pins to 350 to 400 ⁰ C, through a shortening of the pin length and the better cooling effect of the system. Clogging of cooling channels by vapor bubbles is eliminated, which significantly improves the important operational reliability of the reactor.

The invention is not restricted to the embodiment shown. For example, the The cylindrical and the conical pipe sections each have a separate cooling system with corresponding ring collectors and have inlet and outlet nozzles for the coolant. In addition, the additional pins in the thermally less stressed sections of the Cooling screens are provided in a reduced number or, in extreme cases, can also be omitted. Finally you can these pins 7 also by other types of fastening, such as shrinking or pressing in the respective inner wall of the respective cold room, as long as they only ensure the pressure tightness of the connection.

Claims (4)

Expectations 1 J cooling screen as the inner lining of combustion chambers, gas generators, etc., consisting of a cooled jacket with pins attached and an inner layer of refractory ramming material, through this marked that the cooled jacket of two equidistantly arranged flat metal sheets (1, 2) and / or pipe sections (3, 4; 5, 6), which are connected to one another by means of continuous support bolts (7). 2. cooling screen according to claim 1,
characterized, that on the inner sheets (1) and / or pipe sections (3, 5) additional pins (8) are attached gas-tight, the inner end sections as well as the inner sections the trunnions (7) are embedded in the ramming mass (19), and the outer sections of the latter in the Continuous cooling space through which the coolant flows protrude between the two metal sheets (1, 2) or pipe sections (3 to 6). 751- (266 957 4) -Sd-E 35236Ί0 3. Cooling screen according to claim 1 or 2, characterized in that the support bolts (7) or the pins (8) in bores in. The sheets (1, 2) or the pipe sections (3 to 6) are welded. 4. Cooling screen according to one of claims 1 to 3, characterized in that that the outer or the inner conical and cylindrical pipe sections (3 to 6) to one outer each and an inner continuous jacket are connected to one another in a gastight manner, the hollow cylindrical Inner space between the two jackets, each with a lower and an upper ring collector (10, 12) for the coolant supply or process communicated.