JPS59138892A - Method and device for indirectly cooling hot gas - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for indirectly cooling hot gas, in which the hot gas is passed through a heat exchanger equipped with a cheep.

Methods of this kind are well known. The gas is cooled by cooling 2, the transfer of heat to the material. If gas is passed through the tube, coolant surrounds the tube. On the other hand, if the gas is forced to pass through the tube,
Coolant is passed through the tube.

If the hot gas contains impurities, they can even become deposited as solids on the walls of the tubes upon cooling, and can even block them within or between the tubes. This requires regular cleaning of the tube, which usually requires interruption of the gas flow. If the impurities are water soluble, these problems can be overcome by the method of the present invention.

It is therefore an object of the invention to clean heat exchangers without interrupting the gas flow.

The invention thus relates to a method for indirectly cooling a hot gas containing impurities, in which the impurities are deposited in the form of water-soluble solids during cooling, and the hot gas is passed through a heat exchanger equipped with a tube. , a feature of the invention is that a film of water flows downwardly along each cheep, and the water flowing away under the cheep is discharged from the heat exchanger.

The impurities are cooled, solidified and dissolved in the water film,
In this film it is conveyed to the bottom of the heat exchanger and discharged from there. If there are existing deposited impurities, they are also dissolved and discharged. The heat exchanger tubes are thus cleaned without interruption of the gas flow.

The heat exchanger can be positioned in many ways, for example horizontally or vertically. If it is positioned substantially horizontally, so that the tubes are also horizontal, then coolant is preferably passed through the tubes and gas is passed around them. Water is sent from above to the heat exchanger, where it forms a film on the tubes and dissolves the deposited solids. It drips from one cheese to the other and finally ends up at the bottom of the heat exchanger from where it is discharged.

The heat exchanger is preferably positioned vertically. Either gas or coolant can pass through the tube.

In any case, the method according to the invention is much easier to carry out in a vertical position than in a horizontal position.

A water film can be formed by spraying water on top of the heat exchanger. The water droplets thus formed collide with the chives and form a water film. but,
Some water droplets fall to the bottom without contacting the cooling surface and without forming a film. This cannot be completely prevented even in the case of vertical heat exchangers with distribution plates above the tubes. Water droplets are still not filmed and can fall through the tubes or between the tubes.

If gas is passed through the tube, it is easy to ensure that substantially all of the added water forms a film. Therefore, a substantially vertical heat exchanger is advantageously used, in which case the gas is passed through tubes.

In such embodiments, the water in the water film sump is preferably routed onto a tube grate to which a substantially horizontal tube at the top of the heat exchanger is connected.

In this way, water flows uniformly over the tube plate into the cheep, forming a water film. Preferably 1. The end of the tube projects slightly above the tube plate. Advantageously, the ends of the tubes project above the tube plate with their openings in a horizontal plane. The water delivered onto the inner tube plate has the same level across all tube plates;
Thus, the same amount of fluid per tube flows over the edges within the tube (assuming the tubes are of the same diameter).

For this purpose, the end of the tube should be 0/- to 10 cm
Appropriately protrudes above the tape plate.

In order to obtain a more uniform distribution of water on the inner tube plate, the tube plate is preferably divided into sections that can be individually connected to a water source. For this purpose, the tube plate may be divided into segments, but also
It can also be divided by concentric circular partitions or by parallel straight partitions. A combination of these systems is also possible. In the present invention, water is understood to include all aqueous solutions. It may also contain other substances, such as salts or alcohols that raise or lower the boiling point of the water mixture.

The water supply rate is determined by the total wall area within all chives. This percentage is not significant. Preferably, the water film is present over the entire area of the tube. This proportion should not be so large that the tube is completely filled with water when gas is passed through the tube, and the proportion between the tubes must not be so large that the tube is completely filled with water when the gas is passed through the tube. The space should not be so large that the space is almost filled with water.

The method according to the invention can be carried out intermittently depending on the amount of impurities in the gas, the solubility of the deposit in water, and other things.
Or it can be performed continuously. Intermittent methods are preferred if the amount of impurities is small and the deposit is easily dissolved in the water.

The water that falls from within the tube and exits the heat exchanger is preferably at least partially recycled to the top of the heat exchanger. The recycled water is heated slightly by the gas. Solids dissolve more easily in this relatively warm water. This is advantageous if the process is carried out under pressure. Recirculation eliminates the need to pressurize large amounts of water.

Advantageously, a portion of the water discharged from the heat exchanger is not recycled but is removed from the system and replaced with fresh water. This prevents excessive impurities from accumulating in the water relative to the water film. Therefore, it is desirable to periodically or continuously add fresh water to the recirculated water.

In the case of a substantially vertical heat exchanger, the gas passes through the heat exchanger from bottom to top or from top to bottom, i.e. against or in the same direction as the flow of the water film. be able to. Since the water film tends to be disturbed by the gas flowing against it, the gas is preferably passed from the top to the bottom.

The method according to the invention is advantageously applied if the gas is a synthesis gas containing ammonium chloride. Synthesis gas is formed by the reaction of gaseous or liquid hydrocarbons, coal, wood, or other fuels with oxygen.

Synthesis gas consists mainly of carbon monoxide and hydrogen. Regardless of the fuel, it also contains small amounts of ammonia, ammonium chloride, chlorine and halogens - carbon oxides, hydrogen sulfide, methane, carbon oxysulfide, and hydrogen cyanide. This gas is cooled. And at the same time as the outside,
Solid ammonium chloride is deposited. Still other ammonium halide compounds and ammonium bicarbonate will be deposited. The negative effects of this deposition on the heat exchangers used can be prevented by the cooling according to the invention.

Before being introduced into the heat exchanger, the synthesis gas, which normally has a temperature of 3JO to 700°C and a pressure of JO/Par, is preferably cooled to a temperature of 200 to 2θ°C. Under these conditions, the water that forms the water film almost always remains in liquid form.

The invention also relates to an apparatus for carrying out the described method, which apparatus comprises an inlet and an outlet for the gas and
a pressure vessel to which the inlet and outlet of the coolant reservoir are connected, the pressure vessel comprising a tube through which gas is passed, the tubes being connected to two tube plates; vertical to the target, and the device is characterized in that at least seven water inlets are provided above the upper chive plate and at least seven water outlets are provided at the bottom of the pressure vessel. It is.

Preferably, the ends of the tubes project slightly above the top tube plate. Preferably they project 10 m above the tube plate, more preferably 3 cm above Oj.

The invention will now be described in more detail with reference to the accompanying drawings. However, the drawings do not limit the scope of the invention in any way. The drawings do not show pumps, compressors, valves, monitoring instruments, or other auxiliary equipment.

In Figure 1, the pressure vessel / is the inlet l of the hot gas reservoir.
It is equipped with Gas entering the heat exchanger through the gas inlet passes downwardly through the tube 10. tube 10
is connected to the chive plate g. The coolant passes through the tubes 10, is introduced into the heat exchanger through the coolant inlet B, and is discharged from the heat exchanger through the cooling Murayama lower. As can be seen in FIG. 2, tube plate ♂ is divided into 72 segments. The segments are separated from each other by partitions.

Each segment is provided with a water inlet≠, thus water can be routed to each segment individually. Water is sent to Cheve plate ♂ via water inlet t. Due to the cheese 10 projecting slightly upwards of the cheese plate, a layer of water is formed thereon.

As more water is added, it flows over the ends of the cheap 10 and forms a film of water on the inner wall of each tube. The film flows downward and the deposited impurities are dissolved into it. tube 10
The water flowing out is trapped in the space at the bottom of the pressure vessel/.

Water is periodically, sometimes continuously, drained from the pressure vessel via a water outlet j in the bottom. The cooled gas leaves the pressure vessel via the gas outlet 3.

FIG. 3 shows the application of the invention to the field of coal gasification.

In the reactor 20, the pipe,! The coal supplied through the pipes 22 and 23 is gasified at high pressure and high temperature by steam and oxygen supplied through pipes 22 and 23, respectively. Most of the formed slag is discharged from the reactor 2o via a pipe. The synthesis gas thus formed and containing fine slag droplets is led via pipe 2≠ to the cooler no. 2, where the gas is slightly cooled and the slag droplets solidify into particles. Synthesis gas contains, in addition to carbon monoxide and oxygen, some ammonium chloride. Here, the cooler, 2 is shown as an indirect heat exchanger, the coolant enters from Tsukibu 27, pipe 2g
go out from However, cooling of the gas can still be accomplished directly, for example by injection of water and/or still cold gas into the hot gas. The mixture of synthesis gas and solid slag particles passes through the mother plate 29 and is transferred to the separator 3o.
sent to. A variety of systems operating at high pressures and relatively high temperatures are possible for the separator. For example, an electrostatic precipitator can be used, and various granular bed filters can be used, such as stationary, movable magnetically stabilized or electrostatic granular bed filters. Acoustic coalescing, ceramic membrane filters or ceramic fiber filters can also still be used. Additionally, dry plate scrubbers or electrocyclones can also be used. The figure schematically shows a ceramic bag filter. The slag particles separated in the bag filter 30 are discharged from the system via the pipe 3/. The hot gas passes through the cooling device 33 through the eve 32.
sent to. From there the mixed gas is sent via pipe 3≠ to the top of the heat exchanger 3j, where it is cooled according to the invention. The gas mixture flows downward through the tubes in the heat exchanger and is discharged via pipe 3B.

Coolant is supplied to the pipes through the pipe 4'/, and is discharged from the heat exchanger through the Noyabug 2. Any coolant can be used. For example (boiling) water or oil can be used. Water is sent through the iso 37 into the heat exchanger 3j and flows downward as a film along the inner wall of the tube. The water leaves the heat exchanger via 3g of water. This water stream is recirculated and split into a stream that is added to the water in the pipe and a stream that is discharged from the system. Ammonium chloride, which is entrained in the gas and solidified during cooling, is dissolved in the water film and removed by the stream IIO.
eventually removed from the system.

The cooled mixed gas is transferred to Δ Eve 3 for further processing.
It is discharged through B.

In the heat exchanger substantially as described with reference to FIG.
Outer diameter 7.9cm, length/0. J tn's chive is 1
At 230℃, through the gas inlet,
Synthesis gas having the following composition is delivered at ≠'1.2 k's.

CO Otsu/, 4t Volume ratio H227,3 Co22.0 N20 /, 7 Ar /, 0 H2S O,ri COS θ/ NH4Cl O,03; To N2,! ;! ; The pressure inside the heat exchanger is 2≠Parr. 7 at gO°C. ♂
kg//s of water is introduced into one of the 72 segments of the tube plated via one of the water inlets for 2 minutes. After 1 minute, the water supply is stopped for 3 minutes and then started again and supplied for 2 minutes into the next segment of the tube plate. In this way, each segment is played once every hour! Receive water supply for minutes. The total feeding time is 4 minutes per hour. Water is 0.2'l kg/
Contains ammonium chloride/rum of s. The end of the tube projects 2 cm above the tube plate. As a coolant, at 50℃/
Water at a rate of kg/s is sent to the heat exchanger via the coolant. The temperature of the cooling water discharged from the cooling phase ratio lower is 20θ°C. In the water extraction rotor, water at f0°C is removed. The amount of ammonium chloride it carries in one hour is t 4' 7.2 kfl.

Synthesis gas is discharged through gas outlet 3.

It has a temperature of ♂O ℃ and does not contain ammonium chloride.

[Brief explanation of the drawing]

FIG. 1 shows a vertical cross-sectional view of the device according to the invention, diagrammatically %. FIG. 2 shows a cross-sectional view of the device along the line ■-■; and FIG. It shows. /... Pressure vessel, λ... Gas inlet, 3... Gas outlet, ≠... Water inlet, j... Water outlet, B... Coolant inlet, 7... Coolant outlet g, ri...tube plate, 10...chieve, 20...reactor, 30...
-Separator, 3j...heat exchanger, 37...pipe. Agent's name: Kawahara 1) - Ho

Claims (7)

[Claims] (1) A method of indirectly cooling hot gas containing impurities that are passed through a heat exchanger provided with cheeses and which, upon cooling, deposit in the form of water-soluble solids, in which a water film is provided along each cheese. A method of indirectly cooling the hot gas containing impurities, in which the water flowing downwards from the bottom of the tube and leaving the bottom of the tube is discharged from the heat exchanger. 2. A method according to claim 1, characterized in that the gas passed through the tube uses a substantially vertical heat exchanger. (3) A method according to claim 2, characterized in that the water for the water film is conveyed onto a substantially horizontal tube grate at the top of the heat exchanger to which the tubes are connected. . (4) The water for the water film is fed onto a tube grate connected to the tube grate so that the end of the tube projects slightly above the tube grate. Method described. (5) The method according to any one of claims 1 to ≠, wherein the water in the water film reservoir is intermittently supplied to the heat exchanger. (6) a pressure vessel connected with an inlet and an outlet for the gas and an inlet and an outlet of a coolant reservoir, the pressure vessel having a tube through which the gas is passed;
That Cheebu! Connect to one tube grate,
In an apparatus for indirectly cooling a hot gas containing impurities, the pressure vessel is substantially vertical.
Apparatus for indirectly cooling hot gas containing impurities, characterized in that one water inlet is provided above the top tube grate and at least seven water outlets are provided at the bottom of the pressure vessel. (7) The device according to claim 6, wherein the end of the tube projects slightly above the tube grate at the top. (8) Device according to claim 6 or 7, characterized in that the tube plate is divided into sections.