Purification and recovery system for oil-containing high-temperature coal gas at outlet of low-pressure gas-making furnace

Abstract

The utility model relates to the technical field of chemical engineering, in particular to a low-pressure gas-making furnace outlet oil-containing high-temperature coal gas purification and recovery system which comprises a high-temperature dust removal system, an oil and heat recovery system, a washing tower system and a stripping tower system. According to the utility model, low-grade heat in coal gas can be fully recovered, and energy is fully utilized; and the pollution of organic matters contained in the low-pressure coal gas to the environment is eliminated.

Description

Technical Field

[0001] The utility model relates to the technical field of chemical industry, in particular to a purification and recovery system for high-temperature coal gas containing oil at the outlet of a low-pressure gasification furnace. Background Art

[0002] The gas produced by the low-pressure gasifier is low in pressure and contains dust and oil. During the purification process, the temperature is usually reduced to 150°C, and then a large amount of water is sprayed to reduce it to room temperature through a spray dust removal and cooling system and a spray water circulation system, and the solids and organic matter contained in it are removed by spraying. The sprayed water is then sent to a cooling tower for cooling, and the cooled water is then circulated back to the spray tower. Since the low-pressure gas contains a large amount of unreacted water vapor, the heat released by its condensation is large, which leads to a large amount of circulating spray water, high power consumption of the machine pump, and a large amount of water lost by evaporation in the cooling tower. In addition, the organic matter in the low-pressure gas enters the water with the spray cooling, and then enters the cooling tower with the water, and is finally discharged into the atmosphere, causing environmental pollution.

[0003] Therefore, how to provide a low-pressure gasification furnace outlet oil-containing high-temperature gas purification and recovery system to fully recover the low-level heat in the gas, recover the oil, reduce energy consumption, and eliminate the environmental pollution caused by organic matter contained in the low-pressure gas has become a problem that needs to be urgently solved by technical personnel in this field. Utility Model Content

[0004] The utility model aims to provide a low-pressure gasifier outlet oil-containing high-temperature gas purification and recovery system to solve the technical problems of low heat recovery rate, low oil recovery rate and large wastewater treatment volume in the prior art.

[0005] The utility model discloses a low-pressure gasifier outlet oil-containing high-temperature coal gas purification and recovery system, comprising a high-temperature dust removal system, an oil and heat recovery system, a washing tower system and a stripping tower system.

[0006] Furthermore, the high temperature dust removal system includes a cyclone dust collector and a precision dust collector with a filter medium. The high temperature coal gas first passes through the cyclone dust collector to remove large dust particles, and then passes through the precision dust collector to remove small dust particles.

[0007] Furthermore, the oil and heat recovery system includes a steam superheater, a steam generator, a boiler water preheater, a desalted water preheater and an oil-gas separator. The oil and heat recovery system cools the coal gas to above the dew point of the water in the coal gas, condenses the oil in the coal gas and separates it.

[0008] Furthermore, the washing tower system includes a washing tower, an oil-water separator, a washing water cooler and a first water pump.

[0009] Furthermore, the oil-water separator is connected to the bottom of the washing tower.

[0010] Furthermore, the first water pump is located between the oil-water separator and the washing water cooler.

[0011] Furthermore, the water outlet of the oil-water separator is connected to the water inlet of a washing water cooler, and the water outlet of the washing water cooler is connected to the washing tower.

[0012] Furthermore, the stripping tower system includes a steam stripping tower, a hot water heat exchanger, a second water pump and an oxygen stripping tower.

[0013] Furthermore, a hot water heat exchanger is provided between the oil-water separator and the washing water cooler.

[0014] Furthermore, the steam outlet of the steam stripping tower is connected to the steam superheater.

[0015] Furthermore, the boiler water of the boiler water preheater is connected to the steam generator, and the steam outlet of the steam generator is connected to the steam stripping tower.

[0016] Furthermore, the hot water heat exchanger is communicated with the oxygen stripping tower and the steam stripping tower respectively.

[0017] Furthermore, a second water pump is provided between the hot water heat exchanger and the oxygen stripping tower.

[0018] Compared with the prior art, the utility model has the following beneficial effects:

[0019] 1. The utility model can fully recover the low-level heat in the coal gas, fully utilize the energy, reduce energy consumption, and eliminate the pollution of the environment caused by organic matter contained in the low-pressure coal gas;

[0020] 2. The utility model can fully recover the tar in the coal gas;

[0021] 3. The utility model can recycle the water condensed from the coal gas for reuse, thereby reducing water consumption and the amount of sewage treatment. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions of the embodiments of the utility model, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the utility model and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying creative work.

[0023] Figure 1 This is a schematic diagram of the structure of the gas purification and recovery system of the utility model.

[0024] In the above drawings, the meanings of the various marks are: 1-cyclone dust collector, 2-precision dust collector, 3-oil-gas separator, 4-oil-water separator, 5-steam superheater, 6-steam generator, 7-washing water cooler, 8-hot water heat exchanger, 9-boiler water preheater, 10-desalted water preheater, 11-first water pump, 12-second water pump, 13-washing tower, 14-steam stripping tower, 15-oxygen stripping tower. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solutions and advantages of the implementation methods of the utility model clearer, the technical solutions in the implementation methods of the utility model are clearly and completely described below. Obviously, the described implementation methods are only part of the implementation methods of the utility model, not all of the implementation methods.

[0026] Example 1

[0027] This embodiment discloses a system for purifying and recovering high-temperature gas containing oil at the outlet of a low-pressure gasifier. The specific structure is as follows: Figure 1 As shown, it includes high temperature dust removal system, oil and heat recovery system, washing tower system and stripping tower system.

[0028] The high-temperature dust removal system comprises a cyclone dust collector 1 and a precision dust collector 2 with a filter medium.

[0029] The high-temperature coal gas first passes through the cyclone dust collector 1 to remove large particles of dust, and then passes through the precision dust collector 2 to remove small particles of dust.

[0030] The oil and heat recovery system includes a steam superheater 5, a steam generator 6, a boiler water preheater 9, a desalted water preheater 10 and an oil-gas separator 3. The oil and heat recovery system cools the coal gas to a temperature above the dew point of water in the coal gas, condenses the oil in the coal gas and separates it.

[0031] The washing tower system includes a washing tower 13, an oil-water separator 4, a washing water cooler 7 and a first water pump 11. The oil-water separator 4 is connected to the bottom of the washing tower 13. The first water pump 11 is located between the oil-water separator 4 and the washing water cooler 7. The water outlet of the oil-water separator 4 is connected to the water inlet of the washing water cooler 7, and the water outlet of the washing water cooler 7 is connected to the washing tower 13.

[0032] The stripping tower system includes a steam stripping tower 14 , a hot water heat exchanger 8 , a second water pump 12 and an oxygen stripping tower 15 .

[0033] A hot water heat exchanger 8 is provided between the oil-water separator 4 and the wash water cooler 7. The steam outlet of the steam stripping tower 14 is connected to the steam superheater 5. The boiler water of the boiler water preheater 9 is connected to the steam generator 6, and the steam outlet of the steam generator 6 is connected to the steam stripping tower 14. The hot water heat exchanger 8 is communicated with the oxygen stripping tower 15 and the steam stripping tower 14 respectively. A second water pump 12 is provided between the hot water heat exchanger 8 and the oxygen stripping tower 15.

[0034] The amount of low-pressure gas from the gasifier is ~70000Nm 3 / h, containing CO ~ 20% (V), CO2 ~ 20% (V), H2 ~ 30% (V), CH4 ~ 2% (V), N2 ~ 0.5% (V), H2O ~ 25% (V), tar content ~ 2% (V), pressure ~ 0.018MPa (G), temperature ~ 450℃.

[0035] The low-pressure and high-temperature coal gas passes through the cyclone dust collector 1 and the precision dust collector 2 in turn to remove the solid matter in the low-pressure coal gas, and then enters the steam superheater 5, steam generator 6, hot water heat exchanger 8, boiler water preheater 9 and desalted water preheater 10 in the waste heat recovery system in turn. The coal gas is cooled to about 80°C, at which time most of the tar is condensed and separated, and then the coal gas enters the washing tower 13 for washing and cooling to about 40°C to obtain purified coal gas.

[0036] The purified low-pressure gas contains CO~26% (V), CO2~26% (V), H2~39% (V), CH4~2.6% (V), N2~0.7% (V), H2O~5% (V), tar content~0.01% (V), pressure is 0.008MPa (G), flow rate~58400Nm 3 / h.

[0037] The washing water after washing the low-pressure coal gas flows out from the bottom of the washing tower 13, and the tar component is separated by the oil-water separator 4. The washing water separated from the tar is pressurized by the first water pump 11, and a part of it is cooled by the washing water cooler 7 and enters the washing tower 13 as circulating washing water, and the other part of the 13m3 condensed in the coal gas is used as circulating washing water. 3 / h water is heat exchanged with the hot water from the steam stripping tower 14 and then enters the steam stripping tower 14, where it is stripped with about 22t / h of steam required by the gasifier. After stripping, the steam enters the steam superheater 5 and is overheated before going to the gasifier. About 13m 3 / h hot water enters the hot water heat exchanger 8 for heat exchange and cools down to about 75°C before entering the oxidant stripping tower.

[0038] The remaining organic matter dissolved in the washing water is extracted by steam stripping and sent to the gasifier with steam for gasification. The organic matter is finally decomposed at high temperature, eliminating the environmental pollution caused by the organic matter contained in the low-pressure coal gas. At the same time, the organic matter is converted into coal gas in the gasifier, reducing the consumption of raw materials.

[0039] The stripping water entering the oxidant stripping tower is about 8000Nm 3 / h oxygen is used to strip the hot water and reduce the temperature of the hot water from 75°C to about 50°C. The oxygen leaving the oxygen stripping tower 15 contains about 8% water and is sent to the gasifier. The kettle water leaving the oxygen stripping tower 15 is about 12.5m 3 / h sent out of bounds.

[0040] Compared with the conventional system, this embodiment can recover about 2 t / h more heat to produce steam and about 12.5 t / h more water, while reducing exhaust gas emissions.

[0041] The above are the implementation methods listed in this embodiment, but this embodiment is not limited to the above optional implementation methods. Those skilled in the art can arbitrarily combine the above methods to obtain other various implementation methods. Anyone can derive other various forms of implementation methods under the inspiration of this embodiment. The above specific implementation methods should not be understood as limiting the scope of protection of this embodiment. The scope of protection of this embodiment shall be based on the definition in the claims, and the description can be used to interpret the claims.

Claims

1. A system for purifying and recovering high-temperature gas containing oil at the outlet of a low-pressure gasifier, characterized in that: Including high temperature dust removal system, oil and heat recovery system, scrubber system and stripper system; The high-temperature dust removal system comprises a cyclone dust collector (1) and a precision dust collector (2) with a filter medium; The oil and heat recovery system comprises a steam superheater (5), a steam generator (6), a boiler water preheater (9), a desalted water preheater (10) and an oil-gas separator (3); The washing tower system comprises a washing tower (13), an oil-water separator (4), a washing water cooler (7) and a first water pump (11); The stripping tower system comprises a steam stripping tower (14), a hot water heat exchanger (8), a second water pump (12) and an oxygen stripping tower (15).

2. A system for purifying and recovering high-temperature gas containing oil at the outlet of a low-pressure gasifier according to claim 1, characterized in that: The oil-water separator (4) is connected to the bottom of the washing tower (13).

3. A system for purifying and recovering high-temperature gas containing oil at the outlet of a low-pressure gasifier according to claim 1, characterized in that: The first water pump (11) is located between the oil-water separator (4) and the wash water cooler (7).

4. The system for purifying and recovering high-temperature gas containing oil at the outlet of a low-pressure gasifier according to claim 1, characterized in that: The hot water heat exchanger (8) is communicated with the oxygen stripping tower (15) and the steam stripping tower (14) respectively.

5. A system for purifying and recovering high-temperature gas containing oil at the outlet of a low-pressure gasifier according to claim 4, characterized in that: A second water pump (12) is provided between the hot water heat exchanger (8) and the oxygen stripping tower (15).

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