JPS588791A - Conversion of carbonizable materials to synthetic gas and coal - 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 provides solid particulate carbonizable materials in combination with synthesis gas and charcoal (tertiary carbonizable material).
Page) relates to a two-step process for converting into by-products.

The first stage involves relatively low temperature pyrolysis of the carbonizable material and the second stage involves partial oxidation of the plurality of volatiles generated during the pyrolysis.

Coal and lignite, which are widely available at reasonable prices and in near inexhaustible quantities, are powerful liquid and gaseous fuel sources, including what is known as syngas.1. It has been recognized for many years. There has been a considerable degree of interest in converting these materials to syngas over the generations, and interest in syngas programs has increased in accordance with the cost and availability of alternative sources such as methane and naphtha and the demand for syngas. and the amount of research funding increased or decreased. Suffice it to say that there is a wealth of scientific literature suggesting methods for converting coal to syngas.

A vast number of engineering obstacles have hindered the development of this technology.

Widely available carbonizable materials, namely coal, lignite,
Peat and wood are heterogeneous materials containing a large proportion of substances that can be volatilized by pyrolysis.
2) thus encompassing a wide range of organic compounds comprising significant amounts of sulfur-, nitrogen-, and oxygen-containing compounds.

Nonvolatile residues, e.g. coke, contain carbon and ash;
It also often contains nitrogen and sulfur. In summary, herein the name of solid carbonizable material includes:
Bituminous coal, sub-bituminous coal, lignite and wood are all difficult raw materials.

When devising a method for the conversion of solid carbonizable material to synthesis gas, the immediate concern of the Process Technology Office is as to what proportions the feedstock should be converted to gaseous products, principally synthesis gas and impurities, and, incidentally, There is a need to make a choice as to what proportion should remain as a solid by-product. This solid by-product is ash, slag, coke or charcoal. Furthermore, it can be appreciated that complete or substantially complete conversion of solid carbonizable material to synthesis gas is an attractive idea. The economic and engineering parameters are uncomplicated in that the entire production unit is designed and placed almost on the basis of the syngas market and the market momentum for the main products such as coal or coke (page 5). Frees manufacturing equipment designers and operators from random fluctuations. Indeed, much of the prior art has developed products in the direction of complete conversion to syngas.

Parallel to this syngas development, there have been many years of efforts by those skilled in the art to convert mined coal, especially bituminous coal, into relatively valuable solid products such as coke or non-polluting desulphurized coal or charcoal. It has been done. If the product of the process is a value-added solid product, any material volatilized by this conversion process will be a by-product that can be processed in the same manner. In some cases, the volatiles are e.g.
As with the coke oven process, the thermal requirements for this process were mostly met.

Many researchers in the art, like this inventor, have endeavored to provide an economical coal conversion process that produces both d-1 syngas as well as valuable residual coal.

It is believed that the process of the present invention has a number of advantages over previously available conversion methods.

(Page 6) Briefly, it is an object of the present invention to provide both relatively clean gas products and superior charcoal products from solid particulate carbonizable materials.

The term carbonizable is used herein as a general term for carbonaceous materials that thermally decompose into char or coke with the evolution of volatile components. Typical carbonizable materials are wood, peat, lignite, and all coals except anthracite.

The combustion of high sulfur coal was met with ever-increasing unpopularity due to numerous and noisy objections to oxidized sulfur in stack gases.

A common objection has been raised to the combustion of high nitrogen content coal.

This is because its combustion releases nitrogen oxides into the stack gas. There are great expectations for low sulfur and low nitrogen steam coal. However, at the same time sufficient amounts of high sulfur and high nitrogen coal are available. An economical method of converting high sulfur coal and/or high 9-carbon coal, lignite, etc. to low sulfur, low nitrogen combustible coal would be clearly advantageous. Therefore, thermally efficient methods of converting all or part of these materials into relatively clean synthesis gas (page 7) would also be advantageous.

A process for the total conversion of coal with high thermal efficiency, partly to low sulfur and low nitrogen and partly to relatively clean synthesis gas, would meet the unmet needs of this technology.

In summary, the process of the present invention involves the first step of contacting the crushed or pulverized solid carbonizable material, preferably dried and preheated to 300°C, to hot recycle synthesis gas, and thus in the range of about 500 to 1000°C. It is a two-step process that heats the incoming material to the pyrolysis temperature. The carbonizable material may be at least partially devolatilized to selectively remove sulfur and nitrogen from the coal in which the devolatilization occurs. The degree of devolatilization that can be achieved depends, of course, on the material being pyrolyzed, the pyrolysis temperature and the treatment time. Although substantially complete devolatilization is obtained by the practice of the present invention, the carbonizable material need not be completely devolatilized to become a coke product. Typically, this material is a charcoal that retains up to about 20% volatile matter and therefore retains some of the combustion properties of the feedstock.

The thermal energy is recovered from the hot coal product at 500 to 1000° C. and used to dry and preheat the incoming solid carbonizable material as needed, thus improving the thermal efficiency of the process as a whole.

In the second stage of the process, the vapor phase mixture of recycle gas and generated volatiles is partially oxidized at temperatures ranging from about 1000 to 1500°C, particularly when the partial oxidation is carried out with commercially available pure oxygen, at elevated temperatures. This produces gases with high concentrations of hydrogen and carbon monoxide. This gas product is naturally free of tar, phenol and other polymeric components. This gas is then fairly pure synthesis gas. A portion of this synthesis gas is removed with the product of the process and the remainder is used as hot recycle gas to pyrolyze the incoming solid carbonizable material.

For a further understanding of the invention, reference is made to the accompanying drawings, which illustrate the method of the invention in block diagram form.

Referring to the accompanying drawings, the tube 11 (9th
Page) A stream of solid particulate carbonizable material, preferably dried and preheated, and a stream of hot recycle gas from tube 12 are introduced into pyrolysis device 10 . Inside the pyrolysis device 10, the granular material is heated to a range of 500 to 1000°C, pyrolyzed and carbonized, releasing some volatiles that can be liberated from the fuel material, but inevitably Don't release everything.

For convenience, the accompanying drawings show a combined steam and charcoal outlet from the pyrolysis device 10 as from a tubular pyrolysis device.

Produced charcoal is removed from gas-solids separator 20 in line 13, while a vapor phase mixture of slightly cooled recycle gas and generated volatiles is passed from separator 20 via line 14 to partial oxidizer 30. pass. A cumulative stream of acid, preferably commercially available pure oxygen, introduced into the partial oxidizer 30 through tube 15 partially combusts the vapor mixture inside the partial oxidizer 30 to a temperature above 1000°C, typically between 1000 and 1500°C. Raise the temperature of the partial combustion products to a range of . The hot partial combustion products exiting the partial oxidizer via line 16 return to the pyrolysis unit 10 via line 12 and to the recycle stream of the process (page 10).
(high temperature) into a vapor product which exits through line 17 as a synthesis gas product t17.

Although not shown in the block diagram of the accompanying drawings, it is noted that it is optional that the carbonizable solid material used in this method is first dried and preheated, and that this measure saves considerable thermal energy. be able to. Also, although not shown, sensible heat is recovered from the hot gas products. Needless to say, 1000 to 15001? : The gas can generate steam for power generation and (
Alternatively), in overpressure conditions it can be passed through a turbine to generate electrical energy.

The method of the invention thus constitutes a combination of two processing steps that operate almost independently, but are nevertheless coupled together.

The first stage is pyrolysis of the carbonizable material by direct heat exchange with hot reducing gas. The pressures, temperatures and proportions of those gases can be as desired. Above (page 11) Although the gas contains oxygenated compounds, such as -carbon oxides, this gas also contains hydrogen and is a reducing gas as a whole, which therefore has some advantages for this material undergoing thermal decomposition. Apply a reducing gas that is believed to be

Endothermic reactions that reduce coal yield, such as steam coal reactions and carbon dioxide reactions, are suppressed. Hydrogenation reactions such as desulfurization and denitrification reactions are facilitated.

As a result, for some carbonizable materials, such as some bituminous coals, the coal product has a reduced sulfur and/or nitrogen content relative to the feedstock. The selection of particular pyrolysis conditions, such as temperature and reaction time, suitable to enhance desulfurization and/or denitrification of a particular feedstock is considered to be within the practice of this invention.

First, let's consider the desulfurization aspect of this method. It is known to those skilled in the art to remove sulfur from coal by pyrolysis of coal in the presence of syngas, alternatively by reduction or pyrolysis in the presence of an inert sweep gas (e.g., as disclosed in US Pat. 4
, 118, 201).

↑, 1 058...87'H (4) The hot recirculation gas used here is approximately 1:2 to 2
Contains carbon monoxide and hydrogen in proportions that can be adjusted within a 1:1 range. The vapor content of the synthesis gas product is usually about 10 parts, but can be increased to 40% by volume, for example, if desired. The pyrolysis temperature can be adjusted by controlling the temperature and temperature of the recycle gas. Furthermore, the pressure at which the pyrolysis is carried out can be varied within a wide range. Sulfur-containing feed materials that can be carbonized by treatment with reducing sweep gases at overall pyrolysis temperatures can be desulfurized to a sufficient degree to the extent that such materials can be used under conditions to achieve high levels of desulfurization. can be thermally decomposed in the practice of this invention. The pyrolysis step of the present invention is relatively flexible such that pyrolysis conditions consistent with a modest reduction of the sulfur content of the charcoal product are readily available. To reiterate, the hot recycle gas used in pyrolysis is a reducing gas. The combined hydrogen and carbon monoxide content of this hot recycle gas is typically about 5
Exceeds 0 volume coefficient.

(Page 13) The product gas and therefore recycle gas compositions given in the following examples have concentrations of hydrogen sulfide ranging from ■ to 3 volumes, I(S/)T2 volumes of magnitude up to ratio, and H2S/(H2+C
o) Indicates volume ratio. These values depend on the amount of sulfur in the feed, the amount and composition of volatiles formed, and the degree of desulfurization of the charcoal. It is known to those skilled in the art that the presence of H, S in the recycle gas tends to inhibit desulphurization of the coal, especially if the ash of the coal contains significant amounts of iron or calcium ( For example, the first British patent
．． No. 495.997). For example, for low desulfurization of coal from high sulfur coal (less than 1% by weight of this coal), means that do not involve pyrolysis conditions are necessary to remove ash from the feed (
For example, float sink technology (float -5ink)
It can be used as a combination of a high-temperature hydrogen sulfide gas removal device (techniques) or a recirculation waste circuit. The details of such additional machining are outside the scope of this invention.

Dry bituminous coal typically contains nitrogen 1 (14th
100) to 1.5% by weight. Nitrogen oxide (NOx
) Environmental concerns regarding emissions require restrictions on these types of emissions. Although careful control over combustion conditions is suggested to purify NOx from stack gases or to minimize stack gas NOx, this reduction in the amount of nitrogen in the fuel may be of concern to power plant operators. offers many advantages. Unfortunately, standard physical coal purifiers used heretofore are not capable of selectively removing nitrogen. It is not certain that pyrolysis of coal in the presence of an inert gas below about 1000° C. can selectively remove nitrogen from the coal. However, pyrolysis in the presence of hydrogen, as carried out by the practice of the present invention,
Reported to selectively remove nitrogen.

Overall, this pyrolysis step is carried out to produce a charcoal product that is valuable for steam coal purposes. In particular, there is no need to strive to remove the maximum proportion of volatiles from the carbonizable material. In practice, this charcoal contains about 20 volatile substances.
% may be included.

(Page 15) Emphasis in the practice of the present invention is on the nature of the material volatilized from the carbonizable feedstock and on the nature of the char product rather than on the amount theoretically removed. l-Thus, nearly any carbonizable material up to bituminous coal of intermediate volatile content can be used in the practice of this invention.

The pyrolysis reactor can be an entrained reactor, a liquid bed reactor, or any other continuous device capable of devolatilizing the coal by pyrolysis carried out by contact with heated reflux gas.

Details of the equipment used for pyrolysis do not form part of this invention.

The gas removed from the pyrolyzed feed includes significant cooling recycle gas added along with the vapor phase material volatilized from the feed. Thermal analysis of the carbonizable feed to coal volatilizes more organic combustion material than is consumed in the partial combustion stage, and such is therefore an essential aspect of the process.

As already indicated, the vapor phase flow is carried out at 1000 to 1500° C., preferably with commercially available pure oxygen;
It is partially combusted in a partial oxidizer 30 with an 8-8° angle 91(5). The products of this partial combustion are hydrogen and carbon monoxide-rich gases substantially free of such things as tar, phenol, or other undesirable polymeric components. Phenol is
It is destroyed within a few seconds at temperatures above about 1000°C. The partial oxidation is carried out under an environment suitable for consuming the polymeric components volatilized by thermal decomposition. Thus, the proportion of oxygen is controlled and the combustion conditions are controlled to produce a high temperature and relatively clean synthesis gas. A portion of this synthesis gas is removed as a product of the process and the remainder is recycled to the pyrolysis stage.

The pressure of this oxidation step must approach the pressure of pyrolysis and is approximately 7.03 Kq/d gauge pressure (10100 p
si approx. 21.9 KV/aA gauge pressure (300
approximately 3.5 V4/aA with a preferred range of psig)
Gauge pressure (50 psig) or approximately 70.3 Ky/ct
It may be in the range of A gauge pressure (1000 psig).

While operating at overpressure minimizes downstream gas compression demands for this gas user (page 17), operating at pressures higher than the preferred range complicates solids feed equipment and reduces excess hydrogen gasification of coal. (hydro
gasjf jcation) and excessive external methane production.

In the operating temperature range of the oxidation stage, NH,, NCH1CO8
, and small amounts of compounds such as C8 are possible, but nitrogen is first converted to N2 and sulfur is first converted to H,S.
It is believed that it will be transformed into Particularly when maximum coal desulfurization is not a requirement, sulfur compounds may be left in the recycled gas and those sulfur compounds removed from the product gas by known methods such as washing hot carbonic acid solution after cooling. Good too. Alternatively, the high temperature desulfurization device may be used directly in the recirculation gas circuit.

The hot recycle gas stream is driven, for example, by injecting oxygen and/or steam from a pressure source higher than the pressure of the pyrolysis and oxidation stages. Ru.

As already pointed out, desirable specificities of the invention are:
The thermal analysis and synthesis gas production are carried out almost independently of each other, and the desired result from each step (page 18) is the production of high quality coal with some sulfur and (or some) nitrogen removed from the produced coal; and that each step be carried out under conditions suitable for the production of synthesis gas free of polymeric organic compounds. Simply put, the quality of both products can be controlled separately. The practice of the invention may include steam injection, or alternatively coal, as a suspending medium for the incoming carbonizable material, for example just before or after partial combustion, or just before contact of the hot recycle gas with the feed material. Optionally, some measures may even be included which are particularly useful in one or both stages and are therefore not detrimental to the quality of the product, such as preheating the coal so as to reduce its tendency to caking.

Although originally these two stages are operated independently, they of course form an integral whole in a thermal sense. Both stages collectively offer significant thermal advantages to the method. The charcoal has a relatively low temperature, i.e. 1
The sensible heat of the charcoal can be recovered, for example to dry and preheat the feedstock. (Page 19) The gas product stream is generated as a relatively clean, hot synthesis gas, in which case the sensible heat of this gas can be readily recovered, for example by the generation of electrical energy.

Due to the high thermal efficiency resulting from the production of hot gas products and cold solid products by the process of the present invention, this two-step process reduces the amount of oxygen required per unit weight (or volume) of syngas product. In particular, it is possible to increase the yield of charcoal, or, unlike this, to be able to retain some volatile components of the charcoal.
It can be revealed in various ways. All of these aspects are due to the absence of molecular oxygen in the pyrolysis stage, the high degree of protection of the source gases in the pyrolysis stage, and the substantial absence of tars, phenols, and hydrocarbons generated from the material undergoing carbonization during partial oxidation. generally attributed to the complete destruction of the

These components are converted to carbon oxide and ice.

To further understand the invention, reference is made to examples of manure.

? 51iiiBE:58-8791(6) (Page 20) Table 1 Mass balance example number 1 2
Number of 3 stages 1 1 24
5 6 2 2 2 500 700 7001100
1100 1100100 1.0
0 10076.7 1+5.2
143.8=-18,0 79,069,369,3 37,752,473,6 (Page 21) Table 2 Enthalpy Equilibrium -X 10m - 51 Heat 1 Temple Sho r>8-8'? r month [7] 1168 1168 11684
24 745 61766
308 174-27 33 49 89 (2nd
Page 2) Table 3 Product Condition 1 Example Number 1 2 3
Product gas 0.453 K9 morph 45.3Kg
Dry coal H20,601,451,18 CQ 2.13 1.2 (11,
32I (200,130,510,27 Syngas product Mgcf/45.3Kp Coal 1.04
1.00 0.95scf/scf 02
2.94 3,43 3.5
1 Coal Product Total Btu/Btu Coal (HHV) 0.93
0.92 0.93 ■ Less product of coal than coal on a net solid fuel bi-equivalent heating basis.

■■ Assuming that heating up to 1000℃ causes devolatilization of 1oo4 [2] Estimate.

615- 4 5 60.65
1.23 1,370.9
5 1,35 1.070.
11 0.1 ] 0.
400.00 0.01 0
．． 000.04 0.07
0.070.02 0.03
0.030.16 0.21
1,100.50 0,98
0,926.07 6.41
6,043.01 3.9 fl
3.210.78 0,
65 0.65] 8.1
6.6 6.60.95
0.95 0.93 (District 23) 1st to 6th Examples These examples are based in part on the pyrolysis of Illinois No. 6 bituminous coal. Based on data from statistical calculations.

The first and second examples were carried out using commercially available pure oxygen.
The expected performance of single-stage oxidative pyrolysis at 000°C is shown. Partial combustion is used as a heat source for pyrolysis. In the first example, combustion selectively consumes the products of charcoal;
In a second embodiment, combustion consumes the generated steam products and converts the combustion products, thus balancing them in a methanation process.

The third to sixth embodiments illustrate implementation of the present invention.

While the third example shows the effect of pyrolyzing charcoal at 200°C, it shows the effect of oxidizing steam at 1000°C. The fourth example operates the pyrolysis at 500°C. For the fifth embodiment, the coal is preheated to 205 DEG C. before contacting the hot recycle gas. The sixth example shows the effectiveness of steam addition to control partial oxidation. The purpose of the steam addition is to drive the recirculating gas stream and improve the synthesis gas product characteristics.
3'/'91(8) The hydrogen to carbon oxide ratio can be varied and varied to reduce the potential for carbon precipitation.

The results of these six examples are displayed below in terms of mass balance (Table 1), enthalpy balance (Table 2) and product yield (Table 3).

As can be seen from Tables 1.2 and 3 above, meeting the heat demand for pyrolysis through the combustion of solid carbon as in the first example is the same through the combustion of the volatile products. More oxygen (about 28% or more) is required to provide energy and meet the heat demand for pyrolysis. The natural result of this difference is that the conditions of the first embodiment produce a slightly darker product of coal and more tar, oils, and product gases than the conditions of the second embodiment.

The operating conditions of the second embodiment produce relatively high volumes of syngas (per unit of oxygen and solid fuel consumed). Since tar and oil are the materials that are combusted to meet the thermal demands for the practice of the invention, the second embodiment is more comparable to the practice of the invention than the first embodiment. It is more appropriate to

Comparing the results from the second example to the results from the third example, it is observed that the oxygen demand is more favorable for the two-step process of this invention. Oh, l: The gas products are so thick. However,
The two-step process of the present invention comprises a product of about 10% or more charcoal;
Therefore, a gas product of about 10 parts or less is produced. 1. A relatively high proportion of net product is thus obtained in the form of charcoal, and the consumption rate of oxygen and solid fuel per unit of syngas product is reduced.

As can be seen by comparing the degree equilibrium of the third and fourth examples, the thermal decomposition stage occurs at a relatively low temperature), however, the consumption rate of oxygen and solid fuel per synthesis gas product of If operated at the expense of an increase in oxygen consumption, a significant reduction in oxygen consumption can be obtained.

For example, the mass balance for the fifth embodiment in which sensible heat from the product coal is used to preheat the coal is such that (page 26) units of synthesis gas are produced, even though its oxygen demand is therefore reduced somewhat further. It is proven that the consumption rate of oxygen and solid fuel per unit is further reduced.1.2.

As shown by the data of the sixth example, steam addition changes the hydrogen to carbon oxide ratio of the product gas and has no material impact on coal and oxygen usage.

As can be seen from the product yield information in Table 3, the product gases resulting from the practice of the present invention are almost entirely hydrogen and carbon monoxide.

Some of the advantageous results obtained by practicing the present invention are not clearly illustrated by the data presented in Tables 1.2 and 3 above. [7 Therefore, the retention of charcoal volatiles (expressed in product yield, Table 3) is an advantage. This makes the coal even more desirable for boiler fuel purposes. Compared to some proposed devices, the pyrolysis of the present process operates at relatively low flow rates, 7 thus reducing the sensible heat of the charcoal product and generally promoting increased thermal efficiency.

Partial combustion of synthesis gas according to the implementation of the present invention (No. 27)
The relatively high temperature of the synthesis gas enhances the conversion of methane to hydrogen and carbon monoxide and reduces the content of this particular component in the product gas to very low levels.

Recovery of sensible heat from the product gas is of course considered.

[Brief explanation of drawings]

The accompanying drawings are block diagrams of preferred embodiments of the method according to the invention. 10...Pyrolysis equipment, 11.12.13.14.15.
16.17...Tube, 20...Separator, 30...Partial oxidizer. Patent Applicant Air, Products, &. Rhymicals, Incobolized! Page 7) 1980-a゛79t (9) Voluntary procedure amendment dated August 4, 1982. 1. □. Posted by the Patent Office Mr. Kazuo Wakasugi, Incident Indication 1982 Patent Application No. 11382
No. 0 2, Title of the invention Method for converting carbonizable materials into synthesis gas and charcoal 4, Agent

Claims (1)

Claims: 1. A process for converting carbonizable material to coal and synthesis gas, comprising: pyrolyzing solid particulate carbonizable material at 500°C to 1000°C by contact with hot recycle gas; The resulting char is separated from the derived recycle gas and the vapor phase mixture of volatiles, and the vapor phase mixture is partially oxidized to 1000°C to 150°C.
characterized in that it consists of the steps of using a portion of the partially oxidized synthesis gas as a hot recycle gas and removing the remainder of the gas for pyrolyzing the carbonizable feedstock to produce synthesis gas at a gas temperature of 0°C. how to. 2. A process according to claim 1, characterized in that the partial oxidation is carried out with commercially available pure oxygen, so that a relatively pure synthesis gas cannot be obtained. 3 Recycled gas derived from carbonizable material (second
2. A method as claimed in claim 1, characterized in that steam is added to said vapor phase mixture of a volatile substance and a plurality of volatile substances. 4. Process according to claim 1, characterized in that the carbonizable material is preheated before pyrolysis. 5. Pyrolysis of carbonizable materials under conditions of hydrodesulfurization;
2. Process according to claim 1, characterized in that a reduction in the sulfur content of the charcoal thus occurs. 6 Pyrolysis at 700°C to 1000°C under denitrification conditions,
1. A process as claimed in claim 1, characterized in that a reduction in the nitrogen content of the charcoal occurs from 1 to 1. 7. The method according to claim 1, characterized in that thermal decomposition and partial oxidation are carried out under excessive pressure. 8 Hot recycle gas combined hydrogen and -f'i
Process according to claim 1, characterized in that carbon dodecide exceeds 5ONi%.