CN113060785B - Coal gasification flash distillation device and coal gasification flash distillation process - Google Patents
Coal gasification flash distillation device and coal gasification flash distillation process Download PDFInfo
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- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/02—Treatment of water, waste water, or sewage by heating
- C02F1/04—Treatment of water, waste water, or sewage by heating by distillation or evaporation
- C02F1/06—Flash evaporation
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F11/00—Treatment of sludge; Devices therefor
- C02F11/12—Treatment of sludge; Devices therefor by de-watering, drying or thickening
- C02F11/13—Treatment of sludge; Devices therefor by de-watering, drying or thickening by heating
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2103/00—Nature of the water, waste water, sewage or sludge to be treated
- C02F2103/34—Nature of the water, waste water, sewage or sludge to be treated from industrial activities not provided for in groups C02F2103/12 - C02F2103/32
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- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2301/00—General aspects of water treatment
- C02F2301/06—Pressure conditions
- C02F2301/063—Underpressure, vacuum
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2301/00—General aspects of water treatment
- C02F2301/08—Multistage treatments, e.g. repetition of the same process step under different conditions
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
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Abstract
The invention discloses a coal gasification flash evaporation device and a coal gasification flash evaporation process, and relates to the technical field of coal chemical industry. The coal gasification flash evaporation device comprises a flash evaporation tank, a humidifying tower for gas-liquid contact heat exchange and a flash evaporation heat exchanger for gas-liquid non-contact heat exchange, flash evaporation steam output by the first flash evaporation tank and flash evaporation steam output by the second flash evaporation tank enter the flash evaporation heat exchanger for heat exchange after heat exchange through the humidifying tower, a heat exchange pipeline is arranged in the flash evaporation heat exchanger for gas to flow, circulating water is in a heat exchange shell, and circulating water in the heat exchange shell is conveyed to the humidifying tower through a humidifying tower water feeding pump and is used for heat exchange with the flash evaporation steam. According to the invention, the flash steam and the circulating water are not contacted for heat exchange, so that the acidic gas is prevented from being dissolved into the circulating water, and dissolved substances after the circulating water is heated are resolved due to temperature rise and then are not gathered to block a conveying channel, but are directly pumped into the humidifying tower from the humidifying tower feed water.
Description
Technical Field
The invention relates to the technical field of coal chemical industry, in particular to a coal gasification flash evaporation device and a coal gasification flash evaporation process.
Background
At present, a half waste boiler process and a full waste boiler process in the coal gasification market are quite active, but not all coals are suitable for the waste boiler or half waste boiler gasification process, the requirements of the waste boiler or half waste boiler process on the coals are quite strict, once the control is not in place, the waste boiler can block slag, and the whole heat exchange channel can be blocked in serious cases. Therefore, the waste boiler has high requirements on coal for gasification and operation, and the safety, fullness, excellence and long-term operation of the device are seriously influenced.
The waste boiler has the problems, but is still selected for use mainly because the waste boiler can effectively recover the sensible heat of the gasified synthesis gas and the molten slag. In addition, some processes select a semi-waste boiler mainly depending on downstream products, and water vapor is used as a raw material of a downstream conversion device, but a large amount of water vapor needs to be supplemented in subsequent processes due to the fact that the temperature of the water vapor is reduced too much.
In addition, no matter which kind of gasification technique produces the fine ash and all needs further processing, the traditional filtration facility that adopts at present, moisture is higher in the filter cake (fine ash), and most users transport the filter cake that produces to the landfill of the slag site institute made locally through the slag wagon, and the treatment cost is fairly expensive, and the transportation degree of difficulty is very big. Because the filter cake can separate out water in transportation, the road surface pollution is easily caused, meanwhile, the filter cake has incomplete burnt carbon residue, the landfill is quite wasteful, and the filter cake can not be used in buildings, transportation roads, ceramics, special soil improving agents and the like because of high carbon residue. Therefore, secondary dewatering or direct deep dewatering of the filter cake is required, but additional energy (thermal energy and electrical energy) is required for either deep dewatering.
In view of this, the invention is particularly proposed.
Disclosure of Invention
The invention aims to provide a coal gasification flash device and a coal gasification flash process, aiming at preventing black water flash heat exchange equipment from being blocked, improving the safety, stability and economy of the operation of a gasification system, and simultaneously, chilling the sensible heat of gasified synthesis gas and slag by chilling water and then fully utilizing the sensible heat in a flash system.
The invention is realized by the following steps:
the invention provides a coal gasification flash device, which comprises a flash tank for performing flash evaporation on gasified black water, a humidifying tower for gas-liquid contact heat exchange and a flash heat exchanger for gas-liquid non-contact heat exchange, wherein the flash tank comprises a first flash tank for performing high-medium pressure flash evaporation on the gasified black water and a second flash tank for performing low-pressure flash evaporation, and a bottom outlet of the first flash tank is communicated with a feed inlet of the second flash tank; the flash evaporation heat exchanger comprises a heat exchange shell used for containing circulating liquid and a heat exchange pipeline which is arranged in the heat exchange shell and used for circulating gas, a gas outlet of the first flash evaporation tank is communicated with a gas inlet of the humidifying tower, a gas outlet of the humidifying tower and a gas outlet of the second flash evaporation tank are communicated with a gas inlet of the heat exchange pipeline of the flash evaporation heat exchanger, and a liquid outlet of the heat exchange shell is connected with the water feeding pump. In a preferred embodiment of the invention, the heat exchange pipeline in the flash evaporation heat exchanger is provided with a top gas outlet; a heat exchange shell in the flash evaporation heat exchanger is of a storage tank type, a liquid outlet is formed in the bottom of the heat exchange shell, and the liquid outlet in the bottom of the heat exchange shell and the liquid outlet in the bottom of the humidifying tower are both communicated with a synthetic gas washing system through a circulating water pump;
preferably, the liquid outlet of the heat exchange housing is in communication with the humidification tower through a feed water pump.
In a preferred embodiment of the invention, the heat exchange pipeline is in a reciprocating bending shape between the top and the bottom of the heat exchange shell and extends from one side wall of one end of the heat exchange shell to the opposite side wall of the other end of the heat exchange shell, a bottom outlet is arranged at each bottom bending point of the heat exchange pipeline, and each bottom outlet is used as a regular sewage outlet; the shell of the flash evaporation heat exchanger is communicated with a synthesis gas washing system through a circulating water pump.
In a preferred embodiment of the invention, the device further comprises a clarifying tank and a filter cake deep dehydrator, the flash tank further comprises a third flash tank for carrying out normal-pressure flash evaporation on gasified black water, a liquid inlet of the third flash tank is communicated with a bottom outlet of the second flash tank, a bottom outlet of the third flash tank is communicated with the clarifying tank through a flash pump, and a bottom discharge port of the clarifying tank is communicated with a feed inlet of the filter cake deep dehydrator through a feed pump or gravity flow. In a preferred embodiment of the invention, the device further comprises a hot water tank for providing heating water for the filter cake deep dehydrator, and the top gas outlet of the heat exchange pipeline, the top outlet of the third flash tank and the top outlet of the clarifying tank are communicated with a heat source inlet of the hot water tank so as to provide a heat source for heating water for the hot water tank.
In a preferred embodiment of the invention, the filter cake deep dehydrator further comprises a circulating water tank, a liquid outlet of the filter cake deep dehydrator is communicated with the circulating water tank, a top gas outlet of the circulating water tank is communicated with a heat source inlet of the hot water tank, and a liquid outlet of the circulating water tank is communicated with a liquid inlet on the heat exchange shell through a circulating water pump.
In a preferred embodiment of the invention, the system further comprises a first cooler and a first gas-liquid separator, wherein a heating pipeline is arranged in the hot water tank, an inlet of the heating pipeline is a heat source inlet of the hot water tank, an outlet of the heating pipeline is communicated with a material to be cooled of the first cooler, a cooling material outlet of the first cooler is communicated with a feed inlet of the first gas-liquid separator, and a bottom liquid outlet of the first gas-liquid separator is communicated with the circulating water tank;
preferably, the system also comprises an acid gas-liquid separator, wherein a top gas outlet of the first gas-liquid separator is communicated with a feed inlet of the acid gas-liquid separator through an acid gas fan, and a bottom liquid outlet of the acid gas-liquid separator is communicated with the circulating water tank; and the upper gas outlet of the acid gas-liquid separator is sent to a downstream device through an acid gas compressor.
In a preferred embodiment of the invention, the filter cake deep dehydrator further comprises a second cooler and a second gas-liquid separator, wherein a gas outlet of the filter cake deep dehydrator is communicated with a material inlet to be cooled of the second cooler, a cooling material outlet of the second cooler is communicated with a feeding hole of the second gas-liquid separator, and a bottom liquid outlet of the second gas-liquid separator is communicated with the circulating water tank; and the top gas outlet of the second gas-liquid separator is discharged through a vacuum pump.
The invention also provides a coal gasification flash evaporation process, which applies the coal gasification flash evaporation device to sequentially carry out high-medium pressure flash evaporation and low-pressure flash evaporation on the gasified black water, the flash evaporation steam after the high-medium pressure flash evaporation and circulating water are subjected to contact heat exchange in a humidifying tower to generate mixed liquid and noncondensable mixed gas, and the noncondensable mixed gas and the low-pressure flash evaporation steam generated after the low-pressure flash evaporation are both introduced into a flash evaporation heat exchanger to carry out non-contact heat exchange with the circulating water.
In the preferred embodiment of the invention, the temperature of circulating water introduced into the heat exchange shell in the flash evaporation heat exchanger is 85-100 ℃; the operating pressure of the high-medium pressure flash evaporation is 0.4-0.7MPa, and the operating pressure of the low-pressure flash evaporation is 0.2-0.4MPa.
The invention has the following beneficial effects: according to the invention, high-medium pressure flash evaporation and low-pressure flash evaporation are respectively carried out through the first flash evaporation tank and the second flash evaporation tank, flash steam output by the first flash evaporation tank and flash steam output by the second flash evaporation tank enter the flash evaporation heat exchanger together for heat exchange after heat exchange through the humidifying tower, gas in the flash evaporation heat exchanger passes through the heat exchange pipeline, circulating water is in the heat exchange shell, and circulating water in the heat exchange shell is output through the water feeding pump. According to the invention, the flash steam and the circulating water are not contacted for heat exchange, so that the acidic gas is prevented from being dissolved into the circulating water, and after the circulating water is heated, dissolved substances are resolved due to temperature rise and then are not gathered to block a conveying channel, but are directly output by a water feeding pump. Because the flash evaporation heat exchanger is not easy to block, the service cycle of the equipment is prolonged, and the running cost of the equipment is reduced.
In the preferred embodiment of the invention, energy is recycled, the last stage of flash evaporation is normal pressure by matching with the selection of filter cake dehydration equipment, the temperature of filter cake dehydration and drying feeding is high, the dehydration is convenient, and the filter cake can be deeply dehydrated under the condition of not supplementing a heat source under the comprehensive utilization of energy; and meanwhile, the last stage of flash evaporation is normal pressure, so that the water temperature of the recycled circulating water after treatment is high, the water temperature of the recycled water of the system is improved, the higher the washing water temperature is, the less the steam is supplemented by a downstream conversion device, the comprehensive energy consumption of the device is further reduced, the comprehensive energy utilization of the device is reached or surpassed, and meanwhile, the water content in the filter cake is reduced to be below 25%.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and those skilled in the art can also obtain other related drawings based on the drawings without inventive efforts.
Fig. 1 is a schematic structural diagram of a coal gasification flash apparatus according to an embodiment of the present invention.
Icon: 100-a coal gasification flash distillation unit; 110-a flash tank; 111-a first flash tank; 112-a second flash tank; 113-a third flash tank; 120-a humidifying tower; 130-a flash heat exchanger; 131-a heat exchange shell; 132-heat exchange lines; 140-a clarifying tank; 150-hot water tank; 151-heating line; 160-filter cake deep dehydrator; 170-circulating water tank; 181-first cooler; 182-a first gas-liquid separator; 183-acid gas-liquid separator; 184-acid gas blower; 191 — a second cooler; 192-a second gas-liquid separator; 001-humidifying tower feed pump; 002-circulating water pump; 003-flash evaporation pump; 004-feed pump; 005-acid gas compressor; 006-circulating water pump; 007-recycling the filtrate to an underground tank; 008-a filtrate pump; 009-vacuum pump.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.
In the description of the present invention, it should be noted that the terms "upper", "lower", "vertical", "horizontal", "inner", "outer", etc. indicate orientations or positional relationships based on orientations or positional relationships shown in the drawings or orientations or positional relationships conventionally placed when the products of the present invention are used, and are only for convenience of description and simplification of the description, but do not indicate or imply that the devices or elements referred to must have specific orientations, be constructed and operated in specific orientations, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and the like are used merely to distinguish one description from another, and are not to be construed as indicating or implying relative importance.
In the description of the present invention, it should also be noted that, unless otherwise explicitly stated or limited, the terms "disposed," "mounted," "connected," and "connected" are to be construed broadly and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.
The embodiment of the invention provides a coal gasification flash evaporation device 100, which is used for providing a heat source for a hot water tank 150 of a filter cake deep dehydrator 160 after the flash evaporation of gasified black water is performed and the temperature of the flash evaporation steam is reduced, so that the comprehensive utilization of energy is realized, and the deep dehydration of a filter cake can be realized under the condition of no steam supplementation.
The flash tank 110 for flashing the black gasification water includes a first flash tank 111 for high and medium pressure flash evaporation of the black gasification water, a second flash tank 112 for low pressure flash evaporation, and a third flash tank 113 for normal pressure flash evaporation of the black gasification water. The bottom outlet of the first flash tank 111 is communicated with the feed inlet of the second flash tank 112, and the liquid inlet of the third flash tank 113 is communicated with the bottom outlet of the second flash tank 112. Specifically, the operating pressure of the high-medium pressure flash evaporation is 0.4-0.7MPa, and the operating pressure of the low-pressure flash evaporation is 0.2-0.4MPa.
In particular, the specific structure and operating principle of the first flash tank 111, the second flash tank 112 and the third flash tank 113 may refer to the prior art.
It is added that the third flash drum 113 of the normal pressure flash is not adopted in the prior art, but a vacuum flash mode is adopted, namely, high and medium pressure flash, low pressure flash and vacuum flash are carried out. Therefore, the conventional operation requires a vacuum pump to continuously evacuate the third flash tank 113, and the temperature of the steam is also low. The invention adopts a normal pressure flash evaporation mode, the temperature of steam is very high, the invention is matched with the filter cake deep dehydrator 160, the flash evaporation gas after heat exchange of high medium pressure and low pressure and the normal pressure flash evaporation gas are used for providing a heat source for the hot water tank 150, the water in the hot water tank 150 is heated, then the hot water with the temperature of about 90 ℃ is conveyed to the filter cake deep dehydrator 160 to heat the filter cake, and the steam does not need to be supplemented.
Further, the coal gasification flash apparatus 100 comprises a humidifying tower 120 for gas-liquid contact heat exchange and a flash heat exchanger 130 for gas-liquid non-contact heat exchange, the flash heat exchanger 130 comprises a heat exchange housing 131 for containing circulating liquid and a heat exchange pipeline 132 located in the heat exchange housing 131 for circulating gas, a gas outlet of the first flash tank 111 is communicated with a gas inlet of the humidifying tower 120, a gas outlet of the humidifying tower 120 and a gas outlet of the second flash tank 112 are communicated with a gas inlet of the heat exchange pipeline 132 of the flash heat exchanger 130, and a liquid outlet of the heat exchange housing 131 is communicated with the humidifying tower 120 through a humidifying tower water feed pump 001.
It should be noted that the gas in the flash heat exchanger 130 flows through the heat exchange pipeline 132, the circulating water is in the heat exchange shell 131, and the circulating water in the heat exchange shell 131 is conveyed to the humidifying tower 120 through the humidifying tower feed water pump 001 for exchanging heat with the flash steam. The flash evaporation heat exchanger 130 is compatible with the low-pressure circulating water intermediate storage tank for heat exchange, so that the phenomenon that acid gas is dissolved in circulating water is avoided by not contacting the flash evaporation steam with the circulating water for heat exchange, and dissolved substances after the circulating water is heated are resolved due to temperature rise and then are not gathered to block a conveying channel, but are directly conveyed to the humidifying tower 120 by the humidifying tower water feeding pump 001. Because the flash evaporation heat exchanger 130 is not easy to block, the service life of the equipment is prolonged, and the running cost of the equipment is reduced.
In the preferred embodiment of the present invention, the heat exchange pipeline 132 in the flash heat exchanger 130 is provided with a top gas outlet, the heat exchange shell in the flash heat exchanger 130 is of a storage tank type, the bottom of the heat exchange shell 131 is provided with a liquid outlet, and the bottom liquid outlet of the heat exchange shell 131 and the bottom liquid outlet of the humidifying tower 120 are both communicated with the syngas scrubbing system through the circulating water pump 002; the inventors have discovered that by using the liquid from the moisturizer 120 for syngas scrubbing, the temperature of the scrubbing water is high, increasing the vapor content at the outlet of the syngas scrubbing system, and reducing the energy consumption of downstream shift units. What needs to be supplemented is: steam is used as one reactant of the shift reaction, if the temperature of washing water is low, the temperature of synthesis gas discharged from a washing system is low, the saturated water brought out is naturally low, and the shift section needs to be supplemented with steam to ensure the reaction.
In a preferred embodiment of the present invention, the heat exchange pipeline 132 is bent back and forth between the top and the bottom of the heat exchange housing 131, and extends from one end sidewall of the heat exchange housing 131 to the opposite other end sidewall, a bottom outlet is disposed at each bottom bending point of the heat exchange pipeline 132, and each bottom outlet is used as a periodic discharge port, a blowdown valve set is disposed at each bottom bending point of the heat exchange pipeline 132, periodic blowdown is performed, and a high-pressure flushing facility of the blowdown pipe set is disposed at the same time, so as to further avoid blocking of the heat exchange equipment; the flash heat exchanger housing is in communication with the syngas scrubbing system via a recycle water pump 002.
In the preferred embodiment of the present invention, a clarifying tank 140 is further included, the bottom outlet of the third flash tank 113 is communicated with the clarifying tank 140 through a flash pump, and the slurry output from the bottom discharge port of the clarifying tank 140 is communicated with the feed port of the filter cake depth dehydrator 160 through a feed pump 004. The bottom of the third flash tank 113 is transferred to the clarifier 140 by the flash pump 003 or gravity flow, and the aqueous material obtained at the bottom of the clarifier 140 is transferred to the cake depth dehydrator 160 by the feed pump 004.
It should be noted that, after the traditional plate-and-frame filtration is performed by the outlet pressure of the feed pump 004, the filter cake is thermally insulated and heated by the metal plates (the back of the metal plate is provided with a large number of support columns to reinforce the strength of the metal plate, and the gaps between the support columns are channels for heating water) embedded on both sides of the filter cake in the filter cake deep dehydrator 160, and the vacuum pump is started to pump the negative pressure of the filter cake cavity. Because the temperature of the filter cake is about 90 ℃ after the filter cake is subjected to normal pressure flash evaporation, and the filter cake cavity belongs to a closed space, the water in the filter cake can be gasified into steam only by a small vacuum degree.
Further, the coal gasification flash apparatus 100 further comprises a hot water tank 150 for providing heating water for the cake depth dehydrator 160, and the top gas outlet of the heat exchange pipeline 132, the top outlet of the third flash tank 113 and the top outlet of the clarifier 140 are all communicated with a heat source inlet of the hot water tank 150 to provide a heat source for heating water for the hot water tank 150. The heated hot water in the hot water tank 150 is used for heat insulation and protection with the environment when the filter cake deep dehydrator 160 pumps negative pressure for dehydration, and simultaneously heats the filter cake to ensure that the water in the filter cake is vaporized along with the reduction of pressure to absorb heat.
The inventor creatively utilizes the high-temperature steam in the heat exchange pipeline 132, the third flash tank 113 and the clarifying tank 140 to heat the water in the hot water tank 150 to about 90 ℃, and the deep dehydration of the filter cake can be completed without additionally adding other heat sources by matching with the filter cake deep dehydrator 160. The hot water tank 150 is matched with other water replenishing pipelines for replenishing water, a heating pipeline 151 is arranged in the hot water tank 150, the inlet of the heating pipeline 151 is the heat source inlet of the hot water tank 150, and the steam flows away from the heating pipeline 151.
In the preferred embodiment of the present invention, the apparatus further comprises a circulating water tank 170, the liquid outlet of the cake-depth dehydrator 160 is communicated with the circulating water tank 170, the top gas outlet of the circulating water tank 170 is communicated with the heat source inlet of the hot water tank 150, and the liquid outlet of the circulating water tank 170 is communicated with the liquid inlet of the heat exchange housing 131 through the circulating water pump 006. The clear liquid stream produced in the clarifying tank 140 may be sent to the circulating water tank 170 for recycling. The storage facility of the recycle water tank 170 for the recycle water is a key to energy recovery in the whole system, and the liquid output from the filter cake deep dehydrator 160 is transported to the recycle water tank 170 through the filtrate pump 008 after passing through the filtrate recovery underground tank 007, which is a main material source of the recycle water tank 170.
In some embodiments, further comprising a first cooler 181, a first gas-liquid separator 182, and an acid gas-liquid separator 183, the outlet of the heating line 151 is in communication with the inlet of the first cooler 181 to be cooled, so as to condense the remaining small amount of steam using the first cooler 181. A cooled material outlet of the first cooler 181 is communicated with a feed inlet of the first gas-liquid separator 182, and a bottom liquid outlet of the first gas-liquid separator 182 is communicated with the circulating water tank 170; the top gas outlet of the first gas-liquid separator 182 is communicated with the feed inlet of the acid gas-liquid separator 183 through the acid gas fan 184, the bottom liquid outlet of the acid gas-liquid separator 183 is communicated with the circulation water tank 170 (flowing into the circulation water tank 170 by gravity), and the top gas outlet of the acid gas-liquid separator 183 is sent to the next stage (sulfur recovery unit or flare) through the acid gas compressor 005.
In some embodiments, the filter cake deep dehydrator 160 further includes a second cooler 191 and a second gas-liquid separator 192, a gas outlet of the filter cake deep dehydrator 160 is communicated with a material inlet to be cooled of the second cooler 191, a cooling material outlet of the second cooler 191 is communicated with a material inlet of the second gas-liquid separator 192, a bottom liquid outlet of the second gas-liquid separator 192 is communicated with the circulation water tank 170, a top gas outlet of the second gas-liquid separator 192 is conveyed to the atmosphere through a vacuum pump 009, and the first cooler 181 and the second cooler 191 may share a cooling medium, and use a low-temperature organic medium for cyclic power generation.
The invention also provides a coal gasification flash evaporation process, which applies the coal gasification flash evaporation device 100 to sequentially carry out high-medium pressure flash evaporation and low-pressure flash evaporation on the gasified black water, the flash evaporation steam after the high-medium pressure flash evaporation and circulating water are subjected to contact heat exchange in a humidifying tower to generate mixed liquid and noncondensable mixed gas, and the noncondensable mixed gas and the low-pressure flash evaporation steam generated after the low-pressure flash evaporation are both introduced into a flash evaporation heat exchanger to carry out non-contact heat exchange with the circulating water.
The specific working principle is not described herein, and the temperature of the circulating water introduced into the heat exchange shell 131 in the flash heat exchanger 130 is 85-100 ℃ (for example, the temperature of the circulating water overflowing to the circulating water tank through the clarifying tank after normal pressure flash evaporation); the operating pressure of the high-medium pressure flash evaporation is 0.4-0.7MPa (such as 0.4MPa, 0.5MPa, 0.6MPa, 0.7 MPa), and the operating pressure of the low-medium pressure flash evaporation is 0.2-0.4MPa (such as 0.2MPa, 0.3MPa, 0.4 MPa).
The coal gasification flash evaporation process has the following advantages: (1) The coal gasification flash process in the embodiment of the invention solves the problems of blockage of black water flash heat exchange equipment and re-dissolution of acid gas, and the service cycle is obviously prolonged; (2) The embodiment of the invention also solves the problem of recycling and comprehensively utilizing the flash evaporation heat of the black water, and can achieve the aim of deeply dehydrating the filter cake under the condition of not supplementing other steam by comprehensively utilizing the energy of the flash evaporation steam; (3) The water temperature of the synthesis gas washing system is ensured, and the operation of the conversion device can be ensured under the condition of not supplementing steam; (4) The problems of high water content of the gasification filter cake, difficult treatment and resource utilization are solved, the safety, stability and economy of the operation of a gasification system are improved, the online operation rate of the device is ensured, and the production cost of unit products is reduced.
Example 1
The embodiment provides a coal gasification flash process, which applies the coal gasification flash apparatus 100 in fig. 1, and the specific operating parameters are as follows: the temperature of circulating water introduced into the heat exchange shell 131 is 90 ℃, the operating pressure of high-medium pressure flash evaporation is 0.7MPa, and the operating pressure of low-pressure flash evaporation is 0.3MPa.
The results show that: the heat exchange equipment is not blocked after 13 months of operation, the water content of the filter cake can be reduced to 24% without additionally supplementing steam by the filter cake deep dehydrator 160, and the temperature of the synthesis gas at the outlet of the gasification synthesis gas washing tower is 210 ℃ at the lowest under the normal working condition.
In summary, the gasified black water is subjected to high-medium pressure flash evaporation and low-pressure flash evaporation, flash steam output by the high-medium pressure flash evaporation and after heat exchange by the humidifying tower enters the flash evaporation heat exchanger together with flash steam output by the low-pressure flash evaporation for heat exchange, gas in the flash evaporation heat exchanger flows through the heat exchange pipeline, circulating water is in the heat exchange shell, and the circulating water in the heat exchange shell is conveyed to the humidifying tower through the humidifying tower water feeding pump for heat exchange with the flash steam. According to the invention, the flash steam and the circulating water are not contacted for heat exchange, so that the acidic gas is prevented from being dissolved into the circulating water, and dissolved substances after the circulating water is heated are resolved due to temperature rise and then are not gathered to block a conveying channel, but are directly pumped into the humidifying tower from the humidifying tower feed water. Because the flash evaporation heat exchanger is not easy to block, the service cycle of the equipment is prolonged, and the running cost of the equipment is reduced.
The above is only a preferred embodiment of the present invention, and is not intended to limit the present invention, and various modifications and changes will occur to those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (5)
1. A coal gasification flash process is characterized by being processed by a coal gasification flash device, wherein the coal gasification flash device comprises a flash tank for flashing gasified black water, a humidifying tower for gas-liquid contact heat exchange and a flash heat exchanger for gas-liquid non-contact heat exchange, the flash tank comprises a first flash tank for high-medium pressure flash evaporation of the gasified black water and a second flash tank for low-pressure flash evaporation, and a bottom outlet of the first flash tank is communicated with a feed inlet of the second flash tank;
the flash evaporation heat exchanger comprises a heat exchange shell for containing circulating liquid and a heat exchange pipeline which is positioned in the heat exchange shell and used for circulating gas, a gas outlet of the first flash evaporation tank is communicated with a gas inlet of the humidifying tower, a gas outlet of the humidifying tower and a gas outlet of the second flash evaporation tank are communicated with a gas inlet of the heat exchange pipeline of the flash evaporation heat exchanger, and a liquid outlet of the heat exchange shell is connected with a water feeding pump;
the heat exchange pipeline in the flash evaporation heat exchanger is provided with a top gas outlet; a heat exchange shell in the flash evaporation heat exchanger is of a storage tank type, a liquid outlet is formed in the bottom of the heat exchange shell, and the liquid outlet in the bottom of the heat exchange shell and the liquid outlet in the bottom of the humidifying tower are both communicated with a synthesis gas washing system through a circulating water pump (002); meanwhile, a liquid outlet of the heat exchange shell is communicated with the humidifying tower through a water feeding pump;
the device comprises a clarifying tank, a filter cake deep dehydrator, a third flash tank, a liquid inlet of the third flash tank, a bottom outlet of the second flash tank, a bottom outlet of the third flash tank, a feed pump or gravity flow and a feed outlet of the clarifying tank, wherein the third flash tank is used for carrying out normal-pressure flash evaporation on gasified black water;
the top gas outlet of the heat exchange pipeline, the top outlet of the third flash tank and the top outlet of the clarifying tank are communicated with a heat source inlet of the hot water tank so as to provide a heat source for heating water for the hot water tank;
the process comprises the following steps: sequentially carrying out high-medium pressure flash evaporation and low-pressure flash evaporation on the gasified black water, carrying out contact heat exchange on flash steam after the high-medium pressure flash evaporation and circulating water in the humidifying tower to generate mixed liquid and non-condensable mixed gas, and introducing the non-condensable mixed gas and low-pressure flash steam generated after the low-pressure flash evaporation into the flash heat exchanger to carry out non-contact heat exchange with the circulating water;
circulating water is introduced into the heat exchange shell in the flash evaporation heat exchanger at the temperature of 85-100 ℃; the operating pressure of the high-pressure flash evaporation and the medium-pressure flash evaporation is 0.4-0.7MPa, and the operating pressure of the low-pressure flash evaporation is 0.2-0.4MPa;
still include the circulating water jar, the liquid outlet of filter cake degree of depth hydroextractor with the circulating water jar intercommunication, the gaseous export in top of circulating water jar with the heat source import of hot-water tank intercommunication, the liquid outlet of circulating water jar pass through circulating water pump (006) with inlet intercommunication on the heat transfer casing.
2. The coal gasification flash process of claim 1, wherein the heat exchange pipeline is bent back and forth between the top and the bottom of the heat exchange shell and extends from one end side wall of the heat exchange shell to the opposite end side wall of the heat exchange shell, a bottom outlet is arranged at each bottom bent point of the heat exchange pipeline, and each bottom outlet is used as a periodic sewage outlet; the flash evaporation heat exchanger shell is communicated with a synthesis gas washing system through the circulating water pump (002).
3. The coal gasification flash process according to claim 2, further comprising a first cooler and a first gas-liquid separator, wherein a heating pipeline is arranged in the hot water tank, an inlet of the heating pipeline is the heat source inlet of the hot water tank, an outlet of the heating pipeline is communicated with a material to be cooled of the first cooler, a cooled material outlet of the first cooler is communicated with the feed inlet of the first gas-liquid separator, and a bottom liquid outlet of the first gas-liquid separator is communicated with the circulating water tank.
4. The coal gasification flash process according to claim 3, further comprising an acid gas-liquid separator, wherein the top gas outlet of the first gas-liquid separator is communicated with the feed inlet of the acid gas-liquid separator through an acid gas fan, and the bottom liquid outlet of the acid gas-liquid separator is communicated with the circulating water tank; and the upper gas outlet of the acid gas-liquid separator is conveyed to a downstream device through an acid gas compressor.
5. The coal gasification flash process according to claim 2, further comprising a second cooler and a second gas-liquid separator, wherein the gas outlet of the filter cake deep dehydrator is communicated with the inlet of the material to be cooled of the second cooler, the outlet of the cooled material of the second cooler is communicated with the feed inlet of the second gas-liquid separator, and the bottom liquid outlet of the second gas-liquid separator is communicated with the circulating water tank; and the top gas outlet of the second gas-liquid separator is discharged through a vacuum pump.
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