JPS5945712B2 - gaseous fuel generator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to soot-blowing a convective surface of a heat exchanger to remove deposits of particulate matter without reducing the quality of the gas flowing over the surface.

More particularly, the present invention provides a method for controlling the temperature of the generated fuel gas by flowing it over the heat exchange surface and for controlling the convection surface of the heat exchanger with a fluid that does not degrade the quality of the fuel gas. related to periodic cleaning.

Coal gasification systems are currently undergoing technical development urgently in order to provide a new source of energy, and their development is attracting attention.

An important objective of these systems is to generate low BTU fuel gas from solid fuel subequivalent fuels, such as coal.

In gasification units of relatively small size, maintaining a constant cleanliness of the convection surfaces over which the temperature of the produced fuel gas is controlled is a critical issue.

Other gas generation systems undoubtedly have this problem as well.

However, for example 60,0001bs,/hour
Atmospheric coal gasifiers producing a gas capacity of 1,000,000 yen have the significant problem of having to periodically remove accumulated particulate matter from the surfaces of the heat exchangers that cool the product gas.

According to the prior art, air or steam is used to mechanically remove deposited particulate matter from the heat exchanger surfaces by blowing them through a suitably located blower.

However, for example, when producing 60,0001 bs/hour of 100 BTU/SCF of gas, approximately 5,0001 bs/hour of air or steam is required to clean the convective surfaces of the system.

Due to the dilution effect of this large amount of air or steam, the calorific value of the generated gas is reduced by about 100 degrees.

This io% is a very severe and disadvantageous problem for the calorific value of the gas.

The use of air as the soot blowing medium also creates the risk of the mixture reaching a limit where it becomes flammable.

We must take precautions against this danger from both economic and safety considerations.

On the other hand, the use of steam as a cleaning medium risks raising the dew point of the mixture.

It is therefore clear that there is a risk that this condensation will lead to corrosion due to sulfur compounds.

Therefore, in such systems, there is a need for a method to clean the convective surfaces so as to dilute the system's product gases, prevent them from becoming flammable, and preventing the formation of corrosive fluids.

The present invention has been made in view of these circumstances.

The present invention cools and cleans the generated fuel gas, and uses a portion of this cleaned gas for soot blowing to mechanically remove particle deposits on the convection surfaces of the gas generating system. This eliminates the dilution of the fuel gas generated by the above, the fact that the gas becomes flammable, and the generation of corrosive fluid.

Other objects, benefits and features of the invention will become apparent to those skilled in the art from the following detailed description, taken in conjunction with the accompanying drawings.

Preferred embodiments of the present invention will be described in detail below with reference to the drawings.

In order to convert solid coal into gaseous form, the coal is pulverized to a size suitable for combustion in the special combustion equipment used, and its combustion is controlled to subsemiconductor conditions.

As a result, relatively low BTU/SCF fuel gases are produced that can be used in gas turbines or combusted in utility boilers to generate steam.

Of course, the implementation of this process has many technical complexities.

As a result, there are many configurations for supplying coal and oxidant for subequivalent combustion.

In describing the present invention, the gasification unit and the low B
It is not necessary to describe in detail the relevant equipment for producing TU gas.

A gasification unit 1 is therefore shown diagrammatically.

Further, the coal supply source connected to the lower part of the gasification unit 1 is also not shown since it does not require any special explanation.

Combustion can be effected by providing an amount of oxidant to obtain the subequivalent conditions required for generation of low BTU product gas.

The product gas is cleaned downstream of unit 1 and the coal or unburned carbon is recycled to the coal bed in the lower part of unit 1.

Coal is burned in multiple combustion zones within unit 1.

What has been described above, however, is not directly relevant to the present invention, except that gas is produced.

The product gas is produced at a temperature range including about 930°C (1700'F) and preferably about 150'C.
(300°F).

Cooling of the product gas is carried out in unit 1 by flowing the product gas at about 930° C. upwardly for removal through conduit 2.
You can start within.

One or more heat exchangers are placed in this flow path, two heat exchangers 3 and 4 being illustrated in the drawing.

A fluid, typically water or steam, flows through these heat exchangers and absorbs heat from the product gas flowing over the external surfaces of the heat exchangers.

By incorporating heat exchangers 3 and 4 into the system, the water that absorbs heat from the product gas is converted into steam.

This steam can be used to drive a suitable turbine, not shown, as it is not specifically required.

These turbines are usually connected to a generator for producing electrical energy.

The energy obtained in cooling the product gas in unit 1 is thus converted into electrical energy as one of the final products of the system.

It is second to note that the product gas carries solid particulate matter along with sulfur compounds, which are usually present in considerable proportions in coal.

The transported solid particulate material comes into contact with and adheres to the convective surfaces of heat exchangers 3 and 4.

It is well known that these solid material deposits reduce the heat transfer efficiency of heat exchangers.

Therefore, it is necessary to mechanically remove these solid materials to maintain the required heat transfer efficiency.

For this purpose, a soot blower 5 is equipped in the convection passage of the unit 1 to bring the fluid medium onto the convection surfaces of the heat exchangers 3 and 4 in the amount and force necessary to remove the solid material deposits. turn towards

The cleaning system is designated by the reference numeral 10 and receives product gas which is withdrawn from the top of the convection passage of the unit 1 through conduit 2.

This system 10 is essentially a chamber through which the product gas flows and contacts additional heat exchangers 11 and 12.

A cyclone and/or a baghouse can be used in system 10.
mechanically captures the finely divided solid material transported from the product gas as charcoal.

This coal is essentially the unburned carbon of the coal, unit 1
is recycled to the thermal firing process.

This mechanical separation device is not shown as it is not directly relevant to the present invention, but heat exchangers 11 and 12 are shown as representing additional convection surfaces on which the product gases are separated. Solid particles adhere and accumulate.

Not all of the transported solid material will be deposited in the heat exchangers 3 and 4.

Some solid material also accumulates on the surfaces of heat exchangers 11 and 12.

In cooperation with the soot blower arrangement in unit 1, soot blower 13
and 14 are installed in association with heat exchangers 11 and 12.

These soot blowers 13 and 14 direct a cleaning medium to these heat exchangers 11 and 12 so that the solid particle deposits can be mechanically removed.

Only these soot blowing and convection surfaces are shown in system 10 to illustrate the invention.

The ultimate function of system 10 is to reduce the contamination of the product gas and regulate its temperature for delivery to conduit 20 so that it can specifically be used as a fuel.

Delivery of this product gas is simply illustrated as being through a fan 21 for delivery to conduit 20, with conduit 22 connecting fan 21 to a utilization device, not shown.

It is extremely important to maintain the calorific value of the produced gas constant.

Care must be taken to ensure that the calorific value of the produced gas is not reduced by dilution of the gas.

The smaller the unit, the smaller the volume or weight of product gas produced, the more important it is to not inject diluent fluid.

Therefore, the prior art techniques of using steam or water as the fluid medium for soot blowing are completely undesirable for the operation of the system.

While pursuing the application of prior art to the technical problems of this system, the inventor discovered that a portion of the clean product gas generated by this system was soot blown5,13
It suddenly occurred to me that it could be used as a cleaning medium to supply the

The idea was that all problems could be solved based on this idea.

Therefore, according to the present invention, a portion of the product gas flowing through conduit 20 is diverted to conduit 25.

A compressor 26 is provided in conduit 25 and sets the amount of cleaned gas recovered to provide the pressure required by the soot blower.

As shown in the drawings, the outlet of the compressor 26 is connected to a manifold conduit 27 to which each of the soot blowers is connected to receive the required clean product gas.

Of course, valves and controls are required in conjunction with the manifold conduit 27 to divide the clean gas into the various soot blowers and to continue the action of the soot blowers.
Further adjustments are made to the pressure for each soot blower, as well as directing the cleaned product gas as a cleaning fluid to the various fine control and convection surfaces.

Ultimately, the cleaning gas is utilized in each soot blower to act as an effective force to remove deposited particles on the convective surfaces of the heat exchanger.

Its cleaning action is complete and the cleaning gas mixes with the product gas passing through the system without reducing its calorific value.

It has long been conventional practice to soot-blow convective surfaces with steam and/or water.

These media create the problems described above when they mix with the gas that then flows over the cleaned convection surface.

When the contaminant gas flowing over the convective surface is a beneficial gas, its dilution with air and/or steam reduces the quality of the gas to a level that is unacceptable as a fuel gas.

Of course, the fuel gas produced in the gasification unit can be large enough to tolerate dilution effects.

Not only the problem of dilution of the product gas, but also the flammability of the product gas and its dew point are factors that must be protected.

In view of the protection of these elements, the present invention extracts a downstream portion of the generated clean gas and circulates it back to the soot blower.

This use of purified product gas eliminates all problems.

From the foregoing description, it will be seen that the present invention is well devised to accomplish all of the foregoing objectives, along with other benefits obvious and inherent to the apparatus.

Although a preferred embodiment of the present invention has been described in detail with reference to the accompanying drawings, the present invention is in no way limited to this specific embodiment, and various modifications may be made without departing from the scope of the present invention. It is possible.

[Brief explanation of the drawing]

The drawing is a schematic diagram illustrating an example of a system for producing fuel gas and removing particle deposits from heat exchange surfaces in accordance with the present invention. 1... Gasification unit, 2... Conduit,
3,4...Heat exchanger, 5...Soot blower, 10...Cleaning system, 11.12...
...Heat exchanger, 13,14...Soot blowing, 20
... Conduit, 21 ... Fan, 22 ...
... Conduit, 25 ... Conduit, 26 ...
・Compressor, 27... Conduit.

Claims (1)

[Claims] 1. A gaseous fuel at a predetermined temperature is generated from the solid fuel by subequivalent combustion of the solid fossil fuel, and this gaseous fuel flows carrying particles, depositing the particles on the convection surface, and depositing the deposited body. A device for receiving a gaseous fuel carrying the particles and reducing the particles carried by the gaseous fuel, in a device adapted to be removed by a cleaning fluid released from a soot blower, and a device for reducing particles carried by the gaseous fuel by receiving a gaseous fuel carrying the particles, and discharging a fluid that removes accumulated particulate matter from a convective surface. a conduit connected to the cleaned gaseous fuel for recirculating a portion of the cleaned gaseous fuel to the soot blower as a fluid supply to the soot blower. 2. The conduit includes a compressor, the compressor being driven to set the amount and pressure of clean gaseous fuel supplied to the soot blower.
Apparatus described in section.