JPS59155492A - Manufacture of clean and alkali-free fuel 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 pyrolysis process for producing gases from solid or liquid fuels, and more particularly, a high temperature pyrolysis process for producing clean and alkali-free gases. related to.

Recent changes in the world energy market are placing opposing demands on suppliers and users of electricity.

-Increasing overall costs of energy in all its forms has led to a demand for more efficient power plants. On the other hand, the rising cost of petroleum products compared to other less clean energy sources, such as coal, is forcing some suppliers to convert oil to other cheaper energy sources.

The conflict between these two requirements is most apparent in the case of high temperature gas turbine combined cycle power plants. These plants combine the high-temperature generation efficiency of gas turbines with the low-temperature heat recovery efficiency of steam boilers.
This reduces the plant efficiency by 5 to 10 ss. This type of combined sykes plant is not new to Kano for the time being, and has been operated with Seishi stone extraction fuel in the past with good results. The efficiency of these plants depends on the gas turbine inlet temperature; the higher the turbine inlet temperature, the higher the overall power generation efficiency. Increasing the flatness of the gas turbine blades, strings, and jets is required.If the population γ blackness is 109
．． In order for a gas turbine to have a useful operating life above 3°C (,2°00"F), the incoming hot gas must be substantially free of particulate matter and alkali-bearing bone compounds. Therefore, it is necessary to prevent erosion and corrosion inside the turbine.

The requirement that the gas inlet log gas be absolutely pure has so far inhibited the use of alternative fuels in high temperature gas turbine coupled cycle plants. Alternative fuels such as coal, electric oil, tar, oil sands, and wood contain inert compounds that remain in the flue gas after combustion. Since the population of gas turbine generators is generally higher than that of the left air, the removal of these inert compounds must be carried out under high T crystals and high pressures.

Such high temperature, high pressure purification systems are expensive and complex, and have not been widely accepted by the power generation industry. Therefore, direct combustion of these alternative fuels is only utilized in low inlet temperature, low efficiency gas turbine generators.

Seven methods have been proposed for using alternative fuels (e.g., coal) in high-temperature gas turbine combined cycle power plants. The fuel gas is then cooled to a temperature suitable for removing particulate matter contained therein and combusted in a pressurized combustor upstream of the gas turbine inlet. Te of
Several such systems, such as the xaco method, are currently being constructed and tested.

Many of the alternative fuels mentioned above, such as coal, charcoal, and wood chips, consist of volatile, fixed carbon, and inert (or ash) components. The volatiles of these fuels contain hydrocarbons, water, and other compounds that are easily removed during heating of the fuel. The gas generated during the thermal decomposition of these fuels generates heat @Guku5o
It can be an excellent fuel for high-temperature gas turbines when the impurities present (~vine impurities) are suitably removed.

The pyrolysis method for producing fuel gas is simpler than the gasification method described above because it requires fewer system conversions. This involves converting the fixed carbon of a fuel such as coal into gas, which requires large equipment and a complicated process. However, in general, gasification methods have recently received more attention than simple pyrolysis methods for one of the following reasons. In other words, in the pyrolysis method, the fuel chemical thermoelectricity of the strip wall remains as fixed carbon scrap or char (it is too heavy to scrape to dump), and in order to achieve high efficiency, pyrolysis is required. 3°C (/10θ”
F) must be carried out above, at which temperature the alkaline compounds in the supplied fuel are generated together with the volatiles of the fuel.

The advent of fluidized bed technology provided a means to effectively utilize the chemical thermal energy of residual char in pyrolysis processes;
Problems still remain regarding alkalis and other particulates present in the gases generated. Combined cycle power plants that use pyrolysis to produce the fuel, gas, for gas turbine generators have an efficiency advantage in the sense that some of the supplied fuel chemical thermal energy is bypassed through the high temperature gas turbine power cycle. However, the simplicity and low cost of such systems compensate for such operational penalties.

What is currently needed is a method for pyrolyzing solid or liquid fuels at high temperatures to produce a clean and alkali-free fuel gas suitable for use in high temperature gas turbines.

The method according to the present invention thermally decomposes the fuel supplied at high temperature (S73°C or higher) to improve the volatility and produce a clean and alkali-free fuel gas suitable for use in high-temperature gas turbines. is generated.

Alkali-containing fuel is mixed with high temperature gas at a temperature of 393°C (/100 to /g00"F).
heating to cause thermal decomposition of the supplied fuel.

The high-temperature gas is non-oxidized or W-based raw gas obtained by remixing a portion of the citrus gas produced by decomposition of the supplied fuel. The recycled crude gas, in effect a non-combustible gas, is mixed with a stoichiometric amount of an oxidant gas and reacted in a combustion zone to produce the high temperature non-oxidizing gas described above.

The remaining crude gas is cooled to below a temperature at which all of the gas alkali products contained therein condense. The condensed alkaline compounds along with the condensed hydrocarbonaceous material are then removed from the gas stream and any remaining particulate matter or liquids are removed by passing the cooled gas through a mechanical or electrical filter. .

The clean gas thus prepared contains little or no particulate matter or alkaline compounds that would damage high temperature gas turbines.

The cooling gas may optionally be preheated before removing particulate matter to prevent condensation or blockage within the collector.

Next, a description will be given with reference to the drawings.

Solid or liquid fuel is passed through line 10 to the pyrolysis vessel/
2. The fuel used in the process of the invention is preferably unsuitable for direct combustion in a gas turbine generator due to particulate carryover or alkaline content, but produces gases that are suitable for high temperature pyrolysis. It contains sufficient volatile matter to Typical examples of such fuels include coal, heavy keel oil, heavy oil, wood chips, waste hydrocarbons, biomass, and other carbon-based fuels.

The fuel is mixed with the hot gas puffer in a turbulent fluidized bed /6 in the pyrolysis vessel /2. The turbulent fluidized bed provides a high gas-fuel contact rate so that the fuel feed 10 is heated quickly and uniformly. In the same fluidized bed reactor, the hot gas/liquid is made turbulent by a perforated plate/g below the fluidized bed/6.

The temperature in the fluidized bed/B is S93°C (/100″F)
As above, the good luck is tyqqg ℃, (/g Oθ
below].

This preferred temperature provides a high yield of volatiles without causing excessive breakdown of the higher hydrocarbons present in the volatiles of the fuel and without exceeding the melting temperature of the inert materials present in the fuel. I can offer you respect.

The gas generated from pyrolysis, along with fluidizing gas/g,
passing through the internal cyclone 2/, the upper surface of the fluidized bed, 20
duct), 2.2 through the pyrolysis vessel/, 2.
exit. This crude gas stream λlI is divided at two cores into a recirculated gas portion of 2 g and a product gas portion of 30 g. The recirculated gas portion is led to the throat of the gas venturi 3.2. The caropressure ochindant 31/ is introduced from this venturi 3.2 at a rate suitable to create a region of reduced pressure at the throat of the venturi 3.2. This reduced pressure zone induces an inflow of recirculated gas fraction sg into the venturi, producing a mixture of recirculated gas fraction -g and force n pressure oxidant 3 da in a pressurized zone 36 downstream of venturi 3.2. .

A mixture of 2 g of crude gas and 3 g of pressurized oxidant flows into combustion zone 3 g from pressurized zone 3 B. This combustion 1 or the illustrated combustor θ is preferably included. The hot gas/4t generated by the combustion reaction is used to fluidize the fuel/θ in the pyrolysis vessel 7.2, as described above. The flow rates of the recirculation gas fraction 2g and the force[]E oxidant 3q are controlled according to two parameters. First, the recycled crude gas λg must be in an amount necessary and sufficient to provide sufficient thermal energy 2 to maintain the fluidized bed at the desired temperature. The pyrolysis vessel 7.2, together with all piping of the recirculating gas loop, is connected to a thermal fluidizer (42), but the pyrolysis carried out in the fluidized bed IA is endothermic and requires a continuous heat source. The characteristic temperature of gas/li is
It is determined by a special method depending on the material used and the fuel source.

For a fluidized bed that crops near 9gλ"c(/goo"F)+1, the temperature of the thermal fluidizing gas/q is preferably /θ9
3 to /lAO"C(e-', !000 to λ30
0°F). This altitude range provides sufficient thermal energy for special or other refractory heating (which increases the yield of p-pyrolysis products). The first constraint on gas and oxidant flow rates is the thermal fluidization gas/
The requirement is that the fuel be non-oxidizing or reducing. The use of non-oxidizing gas as fluidizing gas for fluidized bed/A prevents oxidation reactions from occurring within the pyrolysis vessel 7.2.

Such oxidation reactions reduce the amount of chemical evolution of gases generated during pyrolysis and soften and agglomerate the inert ash particles in the cut bed/6.

The thermal fluidizing gas/liquid is maintained in a non-oxidizing state by regulating the flow rate of the Calo oxidant to maintain the combustion zone under stoichiometric conditions. Due to the specific nature of the method and fuel, a precise stoichiometry (always below 7.00) is maintained. The division of the crude gas, 21I, is regulated in the drawing by a damper ++, but may also be effected by other known means suitable for this purpose.

The remaining crude gas 30 that is not recycled is led to a condenser where the crude gas 30/l! The temperature is reduced below the alkali condensation temperature of about 393°C (/100°F). As a result of the cooling of the gas, it is collected within the IIZ in the product gas stream 30 and removed from the gas stream.

The alkali-depleted gas Sλ is then optionally passed through a gas preheater J47 which serves to slightly increase the temperature of the gas before entering the final particulate removal unit 5B. Due to the slightly increased temperature, the agglomerates still present in the cooling gas S2 are re-evaporated and the possibility of blockage in the particulate removal device 5 is thus reduced.

Final particulate removal can be carried out in a number of known collectors, but the one shown in the diagram is the Bagnous! A dry removal system such as an electrostatic precipitation system (not shown) is suitable. The removed particulate matter 10 is collected below Bagno Us,
sent for disposal or energy recovery. The clean and alkali-free product gas sg is thus suitable for use in combustors of high-temperature gas turbines and other applications requiring extremely clean gases.

It is clear that the above method forms only part of a fully combined cycle power plant. Therefore, at this time, a brief description of the overall nature and nature of the plant is sufficient to adequately describe the spirit of the process of the invention.
consider it important.

Furthermore, it must be noted that the above-mentioned pyrolysis method makes no mention of sulfur removal, and in fact is not considered in the method of the present invention. Sulfur removal occurs in the remaining parts of the combined cycle power plant described below.

As mentioned above, the pyrolysis process of the present invention produces a clean, alkali-free gas suitable for use as a fuel in high temperature gas turbines. If the fuel 10 contains sulfur-containing compounds, the clean gas sg often contains sulfur in the form of hydrogen sulfide (H2S).

This hydrogen sulfide becomes sulfur oxides such as SO2'4 or SO3 during combustion in a gas turbine combustor (not shown). may exist within the object 60.

As previously discussed, the fixed carbon remaining in the pyrolysis vessel/2 is removed and combusted in a fluidized bed combustor (not shown) for the production of polymeric steam. Such a fluidized bed combustor can also readily tolerate particulate matter 40 collected from the product gas 30 as well as the condensed alkali, tar or oil SO from the condensation step q6, and the fluidized bed/6 effluent 62. By introducing these streams into a fluidized bed combustor in which coal δ1 or other calcium-containing compounds are present, the residual sulfur remaining in these compounds is effectively collected and rendered into a form suitable for disposal.

Another problem with sulfur cleaning is sulfur oxides present in gas turbine waste. This exhaust stream (with a typical temperature of approximately g/l"CQ/300"F, often containing free oxygen) has been investigated for use as a fluidizing gas in a fluidized bed combustor (not shown). has been done. When used in this particular manner, not only is the waste heat recovered from the gas turbine exhaust stream in the fluidized bed combustor and steam generator, but also the sulfur present in the gas turbine exhaust stream is Absorbed by calcium-containing compounds in the body.

The final flue gas from a gas turbine combined cycle power plant therefore contains no sulfur and has a lower oxygen content than is normally the case for simple thermal gas turbine waste heat recovery systems. Overall, by passing only a portion of the fueled chemical warfare energy through the high temperature gas turbine, a portion of the overall plant efficiency loss can be recovered.

The effluent from the fluidized bed combustor, consisting primarily of inert ash compounds and calcium sulfur compounds, is suitable as a safe landfill material and also suitable for other disposal methods. The tars and oils present in the condensate SO are safely consumed in the fluidized bed combustor. Pressurized oxidant stream 31I can be either oxygen or air, as desired.

This complete pyrolysis-combined cycle method most preferably comprises:
It is carried out under pressure and reduces the size of various components through a pyrolysis-combustion-steam generation process.

The pyrolysis loop is preferably operated at a pressure of between 2 and 30 atmospheres (I), which is slightly higher than the gas turbine combustor inlet.
e body) or above.

The fluidized bed combustion and steam generation are slightly lower than that of the gas turbine.
It is carried out on (rope body).

Thus, the high temperature pyrolysis process according to the present invention proves to be an effective and efficient method for producing alkali-free fuel gas suitable for use in high temperature gas turbines. This method is also employed when operating in conjunction with combined cycle power plants that utilize fluidized bed steam generation or equivalent methods.

Although the present invention has been described above in detail with reference to specific examples, the present invention is not limited to these specific examples, and it goes without saying that many changes and modifications can be made without departing from the spirit of the invention.

[Brief explanation of the drawing]

The drawing is a schematic illustration of the method of the invention. /Co...pyrolysis vessel, /G...fluidized gas, /O fluidized bed, 2'l...crude gas, Yug...recirculation gas, 3.2.
・Venturi, 3 days... Pressurized oxidant, lIQ...
Combustor, damper, condenser, j-+...
Preheater, 5A...Final particulate removal device.

Claims (1)

[Claims] A method for producing clean and alkali-free fuel gas from an alkali-containing solid or liquid fuel, the fuel being heated to a temperature of 593 to 9 g2°C (/100 to 7 gOθ'F ) by mixing with a high temperature reducing gas. The volatile matter produced by the pyrolysis is extracted as a crude gas along with the raw gas, and this crude gas is divided into a recirculation portion and a product gas portion, and the recirculation portion of the crude gas is divided into a stoichiometric ratio. The high-temperature reducing gas used to heat the fuel during aromatic pyrolysis is partially combusted under the following conditions, and the produced gas content of the crude gas is brought below the alkali condensation temperature. The cooled and condensed alkali is removed from the cooled product gas, and the remaining non-air water components and condensed alkali are removed from the product gas, thereby removing the clean and condensed alkali. A method for producing a fuel gas that is clean and does not contain alkali.