JPH03500420A - Purification of raw material gas - Google Patents

Abstract

The invention relates to a process for the refining of a raw gas produced from a carbonaceous material by means of a gasification process, refining taking place in a secondary stage separated from the gasifier. In order to reduce the gas contents of tar in the form of organic compounds condensible at lower temperatures, such as ambient temperatures, and of ammonia, the refining is carried out in a secondary stage being a fast circulating fluidized bed, the bed material of which at least mainly being an active material in the form of a material that is catalytic for tar and ammonia conversion, whereby a catalytic conversion of tar and ammonia contained in the raw gas is obtained. In order to decrease the content of hydrogen chloride in the gas, an active material that also can absorb chloride is used. Fresh catalytic and absorbing material is supplied in an amount sufficient to have the hydrogen chloride present in the raw gas absorbed on the material, a corresponding amount of the material containing absorbed chloride being discharged from the secondary stage.

Description

[Detailed description of the invention] Made from raw material gas The present invention utilizes gasification process means to convert raw material gas generated from carbonaceous material into a gasification process. 1. The method of purification in a second stage separated from

Feedstock gas produced from various fossil fuels and used as fuel gas is valuable. It is an oil substitute. This is because solid fuel cannot be directly combusted due to process requirements. is not possible (e.g. lime furnace firing or conversion of existing oil-fired boilers) It is from.

Other types of applications, such as so-called (electricity and In cogeneration (of heat), gas purity is mainly concerned with tar and dust. High demands are always placed on us. Furthermore, from an environmental point of view, NOX1SO during combustion Low concentrations of hazardous emission compounds such as x and various chlorinated compounds There is a demand.

A final point to mention is that gas produced from waste-derived combustion (RDF) This is especially true when it comes to These requirements regarding gas purity require that the source gas be It can be satisfied by purifying it by a method.

Gasifying RDF and subsequently refining the feed gas is done in existing boilers. or in terms of energy recovery from waste by utilizing manufactured gas. Environmentally friendly in terms of co-generation in the plant and/or boiler This means that it is a preferred method.

Furthermore, the use of feedstock gas is often associated with other technical issues. Ru.

At temperatures below 1200°C, carbonaceous materials such as coal, peat) bark, wood or Since tar is always present in the raw material gas produced by RDF gasification, To use the heated gas for combustion by connecting it directly or close to the vaporizer. There is a limit. Avoid operational interference caused by tar buildup on equipment and equipment. This is a big problem because it limits its ability. Nitrogen is released during combustion of hot gas. sulfur (e.g. from peat) and acetic acid combined in the tar if consisting of Ammonia, H,S (peat) or HCff (from RDF) are even more harmful to the environment emissions (NOx1SOx and HCl2 chlorinated hydrocarbons or dioxins, respectively) xin).

Although intense research has been carried out on the conversion of tar and ammonia, until now it has not been commercially available. No method has been developed that achieves a satisfactory raw material gas on a large scale. raw material moth The traditional method for reducing tar concentrations in scrubbers is through wet scrubbers. However, tar removal is insufficient because aerosols are generated in the scrubber. Become something.

Furthermore, water containing high concentrations of organic compounds and ammonia is produced during the manufacturing process.

As a result, said water must then be cleaned before being discharged to the sewer. RDF Also when gasifying Contains a high concentration of. In addition, fuels with high sulfur content, such as peat or coal, can be used as gas Even in the case of hydrogen sulfide, the raw material gas must be purified to remove hydrogen sulfide.

The object of the present invention is to provide a raw material gas solution by means which solves the above-mentioned problems to a considerable extent. The present invention provides a method for refining gas.

This method is achieved by the method of the invention as defined in the following claims. It will be done.

That is, the present invention is suitable for raw material gases containing tar and ammonia, and in special cases, A method for purifying a raw material gas containing a quantity of hydrogen chloride gas, wherein said gas is RDF, which is a fuel derived from raw materials such as bark, wood, peat, or waste; produced by means of any gasification method from Materials (catalytic and also absorptive) such as dolomite present in the feed gas and ammonia, preferably with a residual content of 500 and ammonia, respectively. 300m9/Nm”. Ru. In special cases, absorption of hydrogen chloride occurs simultaneously, almost reaching thermodynamic equilibrium. do. Said second stage comprises at least a bed of active material, for example in the form of dolomite. Consisting of a circulating fast fluidized bed (CFB) with bedmaterial It is. For this arrangement, the second stage is integrated with any CFB-vaporizer. It is also possible for only a primary particle separator or other type of vaporizer to be placed upstream. It is Noh.

We provide sufficient conversion of tar and ammonia, and in special cases simultaneous chlorination. It was discovered that hydrogen absorption can be achieved. First, it gasifies tar-containing gas. The large fuel particles are separated by heating in a second stage, and then a separated second The circulating high speed fluidized bed is heated in stages with a suitable active material such as dolomite and suitable process parameters. It is made in the form of contact with a meter.

contact and absorption materials if the carbonaceous feedstock contains significant amounts of sulfur, e.g. peat; Absorption of hydrogen sulfide also naturally occurs above.

The amount of active material required in relation to the amount of feed gas depends on the contact with tar and ammonia. It is determined by the space velocity required for tactile conversion, and is determined by several parameters such as temperature. temperature, gas residence time, active material particle size, reactant partial pressure and degree of active material degradation. Depends on. If the temperature is too low and/or the CO, partial pressure is too low, the tar will change. This leads to the formation of carbon deposits on the active surface, thereby degrading the activity. If this If conditions arise, the material is treated with an oxidizing gas such as air and/or steam. It is possible to activate it by doing this. HCQ (and/or H,S) absorption at the temperature of 1nte- rest) so fast that these reactions are mostly determined by equilibrium As a result, the formed chloride solid (and sulfide in the case of H, S) The corresponding active material will be consumed.

That is, we apply chloride (and in some cases sulfur) onto active materials such as dolomite. The absorption of hydrogen chloride (hydrogen oxide) is a fast reaction and is less It was discovered that the active material only needs to be present in a considerably smaller amount with respect to the flow rate. It was.

The use of the second stage in the form of a fast circulating fluidized bed (CFB) has shown considerable advantages. arise.

Such a floor allows for the handling of airborne dust from the vaporizer; provides a very uniform temperature in the reaction zone and a homogeneous phase of gas and bed material. contact, which means that the degree of conversion/absorption varies. This means there is less danger. Furthermore, at a given temperature and space velocity, the conversion is It is also possible to vary the particle size significantly downwards if necessary to increase be. Corresponding corrosion of the flooring material also results in increased availability of the active surface. Become. The second stage, which also has the advantage of being designed as a CFB, can be used with any CFB vaporizer. This can be integrated with a primary powder separator or other type of vaporizer. Just do it. When scaling up, it is possible to achieve relatively small particle sizes. Although it allows the gas flow rate to be relatively high, up to about 10 w/s, preferably 611I/S This is because it can be maintained up to

If the vaporizer consists of a CFB vaporizer, it is configured by directly connecting it after the first dust separation. . If active substances are used as bed material in a CFB vaporizer, the second stage is vaporization. The dust from the second particle separator, e.g. after the second stage, is transferred to the vaporizer in an advantageous manner. It is possible to integrate so that part or part circulates. In this method the floor The total amount of material lost is also reduced, and by using only one floor material mold. You can also get some benefits.

Second stage reaction for satisfactory catalytic conversion of tar and ammonia The amount of active material required in the column depends on the total amount added and the recirculation of bed material. controlled by Suitability of temperature, particle size and amount of active material depending on required transformation Decide on a suitable combination. Attrition, deactivation and/or absorption of HCQ (and H, The active material consumed for or alternatively by adding activated such materials. Gas residence time is controlled by the diameter/height combination above the gas inlet.

In special cases where H(12) is present in significant amounts in the feed gas, the The active material floating in the exhaust gas improves the absorption of the HCff. There are consequences.

Thermodynamically, this means that the gas is purified to an inherently lower temperature before final dust removal. Under conditions of cooling, it will reach a fuller degree at lower temperatures. It is.

Embodiments of the present invention will be described below with reference to the accompanying drawings, but the invention is not limited thereto. isn't it. The figure shows a vaporization and gas purification system to illustrate an embodiment of the invention. Shown schematically.

In the illustrated system, a carbonaceous feedstock l is conveyed to a vaporizer 3, said vaporizer being circulated. It is composed of ring fast flow (CFB). This is the reactor 5L first separator 52 and separated in said first separator; comprising recirculation means 53 for the bed material; ing. The bed material consists of an active catalyst and an absorbent material, in the form of oxides. First separator 5 2 is a non-centrifugal mechanical separator, suitably a U-shaped beam separator, which is used in our European CFB boiler number one described in Patent EP O103613: Related and They match and are cited here for reference.

The high temperature raw material gas 2 produced in the vaporizer 3 is also directly drawn out from the first separator 52, Direct feed to the second gas cleaning stage 25 without any additional dust removal be done.

The second stage 25 is designed as a circulating fast fluidized bed (CFB) 26, and the It has the same type of active bed material as the vaporizer 3 described above.

The feed gas 2 is fed to the second stage 25 so that it constitutes the fill gas.

The second stage 25 consists of a long, narrow reaction column with an arbitrary cross section (e.g. circular or square). (designed to have)

Most of the bed material that follows the steam gas discharged from the top of the reaction column consists of the first particles. Separator 27, preferably a U-shaped beam separator of the same type as the U-shaped beam separator of said vaporizer. separated in a vessel and subsequently separated in a second separator 28, preferably a cyclone. . The material 30 separated in the first particle separator is passed through a recirculation device to a circulating bed 26. is circulated to the bottom of the

The material 29 separated in the second particle separator 28 mainly flows to the lower part of the vaporizer 3 as 31. can be added as If necessary, a portion of said material stream 29 may be circulated as stream 34. It can also be fed to the lower part of the annular bed 26 and/or as stream 43 to the system. It can also be discharged outside.

a suitable height for supplying fresh catalytic material and absorbent material 14 to second stage 25; A side feeding device 15 is used. consumed and/or inactivated The bed material 35 is delivered to the means of a discharge device 36 arranged connected to the bottom of the second stage 25. more excreted.

The active material used during the second step of this example is calcium-magnesium carbonate. composed of a carbonate-containing material, preferably with a particle size of 2μ or less, preferably lmu Dolomite with A fluidized bed 26 is formed.

The gas flow rate in the upper part of the reaction tower is designed with a free cross section and is preferably less than 1 oz/s. Or, it is adjusted so that it does not exceed 6 m/s.

The fluidizing gas in the high-speed circulation bed 26 includes the feed gas 2 and the added oxidizing gas 13, e.g. For example, it is composed of air. If necessary, oxidizing gas 33 is supplied to one or several suitable locations. It can be added to the second stage 25 at a higher level.

Conversion of tar and ammonia contained in raw material gas 2 and in the raw material gas The absorption of the chlorides contained is at 600-1000°C, preferably at 700-900°C1. The catalyst and absorbent material are also preferably heated in the circulating bed 26 at a temperature range of 850-950°C. This is carried out by means of contact with the material. The required temperature level is the same as that of the second stage 25. Maintained by internal combustion of combustible gas components, which are added to the oxidizing gas stream It is controlled by adjusting the amounts of 13 and 33.

The average suspension density in the reaction column of the second stage 25 ranges from 20 to 300 kg/m3, preferably or between 80 and 250 kg/+++3, and the pass-through gas and active material to get the necessary contact. This is the total amount of recycled materials plus 30% of recovered materials. and 34 in combination with the control of the flow rate.

The gas residence time in the reaction tower is calculated to be in the range of 0.2 to 20 seconds assuming that the reaction tower is empty. range, preferably within the range of 0.5 to 7 seconds.

If necessary, the deactivated catalyst and absorption material can be reactivated using an oxidizing gas 32, e.g. air. In addition to said material recycled to the bottom of the circulation bed as streams 30 and 34 more accomplished. The amount of oxidizing gas 32 added is such that the activation is in the range of 600 to 1000°C. It is preferably controlled to occur within the range of 750 to 900°C.

Before starting the aforementioned operation, the heating of the second stage 25 containing the bed material is carried out by heating the LP gas therein. This is carried out using No. 24 combustion means.

The purified gas stream 4 leaving the second separator 28 of the second stage 25 contains floating fines. The split bed material and steam are removed in the next gas processing stage.

The gas passes through two heat exchangers. Oxidizing gas in the first heat exchanger 37, stream 1 0 and the gas passes into the vaporizer 3 and the second stage 25, In this case, the oxidizing gas 11 coming out of the heat exchanger 37 has an appropriate temperature, preferably 400°C. It is preheated to The preheated gas 11 is supplied to the vaporizer 3 (especially as a filling gas). ) into stream 12 and into second stage 25 stream 13. In both 32 and 33 used.

In the subsequent second heat exchanger 38, the temperature of the gas 5 is adjusted, for example, by a standard woven furnace cloth or can be further cleaned by using a cyclone to remove dust at step 39. temperature, preferably 150 to 300'C! be lowered to. Removal Object J118 is removed from dust removal stage 39.

As mentioned above, the gas stream 4 contains finely divided active substances that come out in suspension. , which follows the gas stream exiting the second stage separator 28 . Special cases, e.g. For example, when connected to an RDF vaporizer, the raw material gas 2 from the vaporizer contains a considerable amount of HCQ. Contains. The absorption of HCQ onto carbonaceous materials such as dolomite is endothermic. Therefore, on the material floating out due to gas cooling in the heat exchangers 37 and 38, This contributes to an increase in the degree of absorption of residual HCΩ.

The mostly dust-free gas 7 leaves the dust removal stage 39 and is supplied to the scrubber 40. There the dust is removed from moisture and other water-soluble components. The scrubber 40 Humidification of the gas stream 7 and condensation of the vapor take place therein. Under the current conditions , almost all residual fines precipitate and water-soluble gas components such as NH3, HCQ and Absorption of CQ also occurs.

The water stream 20 emerging from the scrubber 40 is recirculated by a pump 41 where it is heated The temperature of the water 19 recycled to the scrubber 40 in the exchanger 42 is set at 15-20°C. Cooled to maintain range. Excess water 21 is discharged from the water circulation system.

The gas 9 leaving said scrubber is industrially pure, i.e. tar, anhydride, etc. It can be considered to contain almost no monium, dust, HCQ, H, and S. Ru. However, at the outlet temperature here (approximately 30°C), it is saturated with steam. . Depending on the application, the gas stream 8 may be preheated or further dried to reduce the relative humidity. It is also possible to reduce its moisture content by passing it through a drying stage. pure gas is required by engine operation, e.g. by means of a turbocharged diesel engine. combustion without any cleaning of the resulting waste gas. I can do that.

For simpler applications, e.g. for heat generation in boilers, the scrubber 40 can be omitted, so that the purified gas flows after the flow 22 from the heat exchanger 37 or after the dust fraction. Stream 23 from separator 39 can be used directly.

In the example shown, the second stage 25 is integrated with the carburetor 3 based on CFB technology. It came. The vaporizer 3 can contain various fuels such as crude bark, peat or waste-derived fuels RD. Raw material gas 2 can be produced from F. As the bed material in the circulation bed of the vaporizer 3, the above-mentioned material is used. As such, it is convenient to use the same types of catalytic and absorbent materials as in the second stage 25. be.

The overall pressure drop of the oxidizing gas, e.g. air, fed through the production loop is approximately 1 bar. Slightly higher than the standard. Therefore, the oxidizing gas pressure in stream 9 is not required from the viewpoint of this purpose. The compressor 16 can be used to increase the pressure level in the stream lO to is necessary.

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Claims (1)

[Claims] 1) From the gasification process, the raw material gas generated from the carbonaceous material by means of the gasification process A method for purification in a separated second stage, Tar and ammonia are forms of organic compounds that can be concentrated at low temperatures e.g. ambient temperature. During the second stage of purification in the form of a rapidly circulating fluidized bed to reduce the content in the gas of and said bed material is at least largely free of tar and ammonia conversion. consists of active materials in the form of materials that are catalytic for A combination of oxygen-containing gas and/or steam is also possible. the amount of catalytic material present at any given time, its particle size, and the contact between the gas and the solid material. The design of the second stage with respect to the oxidation, the operating temperature, the amount of oxidizing gas that can be added and said gas. The tar and ammonia present in the feed gas are preferably or at concentrations of 500 and 300 mg/Nm3, respectively, in the purified gas. A method for purifying raw material gas, characterized by performing catalytic conversion up to 2) Activity that can also absorb chloride to reduce the content of hydrogen chloride in the gas. Utilize the material, adjust the operating temperature, and intermittently or continuously supply fresh catalyst material and The absorbing material is supplied in sufficient quantity so that the hydrogen chloride present in the feed gas is absorbed onto the material. preferably until the concentration of hydrogen chloride in the feed gas is almost the same. The process is carried out until it corresponds to the amount of mechanical equilibrium, while at the same time the activity remains stationary due to catalytic conversion. a substantial amount of said material containing absorbed chloride while maintaining a sufficient amount of the material present; according to claim 1, characterized in that the second stage is intermittently or continuously discharged from the second stage. Method. 3) The operating temperature of the second stage is in the range of 600 to 1000°C, preferably 850 to 95°C. The method according to claim 1 or 2, characterized in that the temperature is adjusted to a range of 0°C. 4) The operating temperature of the second stage is controlled by the amount of oxygen-containing gas added. A method according to any one of claims 1, 2 or 3. 5) A material in which the active substance contains magnesium-calcium carbonate, preferably preferably consisting of dolomite and/or corresponding calcined (baked) products; A method according to any one of the preceding claims, characterized in that: 6) Cut off active material that has been deactivated as a result of carbon deposition or any other reason. continuous or continuous discharge from the second stage and an equal amount of fresh and/or as claimed in any one of the preceding claims, characterized in that the substituted material is the method of. 7) The deactivated active material discharged from the second stage is treated with an oxidizing gas, preferably oxygen-containing activated by treatment with gas and/or steam in a separate activation stage. , and returning the activated material to the second stage. Method. 8) Deactivated active material as a result of carbon deposition or any other reason. a second stage of circulating the oxidizing gas, preferably oxygen-containing gas and/or steam; before being characterized by activation by processing in a separate floor material system. A method according to any one of the following claims. 9) The activation is performed within the range of 600 to 1000°C, preferably 750 to 900°C. Claim 7 or Claim 8, characterized in that the process is carried out at an operating temperature within a range. Method. 10) controlling the operating temperature of the activation by means of the amount of oxygen-containing gas added; 10. A method according to claim 7, 8 or 9, characterized in that: 11) The raw material gas is transferred from the vaporizer to the second stage without any intermediate dust removal. A method according to any one of the preceding claims, characterized in that it is supplied directly to. 12) The vaporizer consists of a high-speed circulation fluidized bed, and the raw material gas The second stage can be fed directly from the first separator of the vaporizer without any additional 12. The method according to claim 11, characterized in that: 13) that the second stage fill gas consists of feed gas and possibly oxidizing gas; A method according to any one of the preceding claims, characterized in that: 14) Transfer the oxidizing gas that does not constitute the fluidizing gas to the fluidizing gas supply port of the second stage reactor. Claim 13 characterized in that the addition is made at one or several levels above the Method described. 15) Select the total amount of active material present in the second stage dark and for catalytic conversion by controlling the recirculation flow of the bed material to provide a suspension density. The foregoing characterized in that the desired contact between the passing gas and the active material is achieved. A method according to any one of the claims. 16) The gas flow rate during the second stage is 10 m/s or less, calculated assuming that the reaction tower is empty. Any of the preceding claims characterized in that it is preferably maintained below 6 m/s. The method described in one. 17) The particle size of the catalyst material and absorbent material is less than 2 mm, preferably more than 1 mm. Method according to any one of the preceding claims, characterized in that it is small. 18) The average density of the suspension in the reaction column is 20 to 300 kg/m3, preferably 80 Any of the preceding claims characterized in that it is maintained in the range ~250 kg/m3 The method described in one of the following. 19) The residence time of the gas is in the range of 0.2 to 20 seconds calculated based on an empty reaction tower, of the preceding claim, characterized in that it is preferably maintained within the range of 0.5 to 7 seconds. Any one of the methods described. 20) The content of hydrogen chloride in the purified gas leaving the second stage is determined by the particles of the second stage. by means of absorption on catalytic and absorbent materials remaining in the gas after separation. The gas after the second stage is first heated to a considerably lower temperature, preferably 15°C. Special cooling to a temperature between 0 and 300°C and then further separation of dust. A method according to any one of the preceding claims characterized in that 21) The raw material gas supplied to the second stage is transferred to the second stage of a vaporizer having a high-speed circulation fluidized bed. 1 particle separator, where the circulating bed material contains the same active material as in the second stage. characterized by consisting of During the second stage, preferably the dust separated in the second particle separator is at least partially characterized in that it is recycled to the bottom of the vaporization reactor, and The floor material floating in the raw material gas from the vaporization pipe and the can bottom of the vaporizer The material that can be discharged from the second stage is recycled to the vaporization reactor from the second stage and the material that can be discharged from the vaporization reactor is In combination with fresh catalytic and absorbent materials added intermittently or continuously A method according to any one of the preceding claims, characterized in that the method comprises: