阅读说明：本技术 一种煤制气装置细渣干燥方法 (Fine slag drying method for coal gas making device ) 是由 王煊 贺鑫平 周敬林 张镇 骆彩萍 于清 郭平利 余涛 陈斌 刘艳军 于 2019-09-18 设计创作，主要内容包括：本发明公开了一种煤制气装置细渣干燥方法,具体为：来自煤制气装置的高温高压含固黑水经过减压后依次送入高压闪蒸器、低压闪蒸器、真空闪蒸器闪蒸,然后依次经澄清槽沉降、细渣过滤机过滤,进入细渣闪蒸气干燥机,利用闪蒸气的余热通过间接热交换将细渣升温并蒸发细渣中所含的水分,进而实现细渣的干燥。本发明方法充分利用煤气化系统的高/低压闪蒸气的热量对细渣进行干燥,干燥流程相对简单,热效率相对较高,脱水过程中的能量损失低,可以实现对细渣中的可燃组分进行再次利用,提高工厂的经济效益,达到节能减排的目的。(the invention discloses a fine slag drying method for a coal gas making device, which specifically comprises the following steps: high-temperature high-pressure solid black-containing water from a coal gas production device is decompressed and then sequentially sent into a high-pressure flash evaporator, a low-pressure flash evaporator and a vacuum flash evaporator for flash evaporation, then sequentially settled by a clarifying tank and filtered by a fine slag filter, and enters a fine slag flash evaporation gas dryer, and the fine slag is heated and the moisture contained in the fine slag is evaporated by utilizing the waste heat of flash evaporation gas through indirect heat exchange, so that the drying of the fine slag is realized. The method of the invention fully utilizes the heat of the high/low pressure flash steam of the coal gasification system to dry the fine slag, has relatively simple drying process, relatively high thermal efficiency and low energy loss in the dehydration process, can realize the reutilization of combustible components in the fine slag, improves the economic benefit of factories, and achieves the purposes of energy conservation and emission reduction.)

1. The fine slag drying method for the coal gas making device is characterized by comprising the following steps:

Step 1, decompressing high-temperature high-pressure solid-containing black water from a coal gas production device, and then sending the decompressed black water into a high-pressure flash evaporator, wherein part of high-pressure flash steam obtained by high-pressure flash evaporation enters a fine slag flash steam dryer, and the other part of the high-pressure flash steam is sent out of the dryer; the black water after high-pressure flash evaporation concentration enters a low-pressure flash evaporator for further flash evaporation after being decompressed; part of the low-pressure flash steam flashed from the low-pressure flash evaporator enters a fine slag flash steam dryer, and the other part of the low-pressure flash steam is sent out of the room; the black water after low-pressure flash evaporation concentration enters a vacuum flash evaporator for further flash evaporation, and vacuum flash evaporation gas is sent out;

In order to ensure the cleanliness of the high-pressure flash steam and the low-pressure flash steam, the high-pressure flash evaporator and the low-pressure flash evaporator are respectively provided with a tower tray, and dust carried in the flash steam is removed by water washing;

Step 2, the black water after vacuum flash evaporation automatically flows to a clarifying tank, the clear water on the upper part of the clarifying tank overflows and enters an ash water tank, fine slag slurry on the bottom of the clarifying tank is sent to a fine slag filter through a feeding pump, filtrate produced by the fine slag filter enters the clarifying tank, and fine slag discharged from the fine slag filter enters a fine slag flash evaporation gas dryer through a fine slag screw feeder;

Step 3, the fine slag flash evaporation gas dryer heats the fine slag and evaporates water contained in the fine slag through indirect heat exchange by utilizing the waste heat of the flash evaporation gas, so as to achieve the purpose of drying the fine slag; after the flash evaporation gas of the dried fine slag is subjected to gas-liquid separation by a flash evaporation separator, the gas phase is sent out, and the liquid phase enters an ash water tank; moisture generated in the fine slag drying process is cooled by the waste gas cooler and then enters the waste gas separator, gas phase is directly discharged to the atmosphere, condensate is returned to the grey water tank, and the dried fine slag is directly sent to the outside for utilization.

2. The method for drying the fine slag of the coal gas production device according to claim 1, wherein the pressure of the high-pressure flash steam in the step 1 is 0.6-1.5 MPaG, and the temperature is 165-205 ℃; the pressure of the low-pressure flash steam is 0.1-0.5 MPaG, and the temperature is 120-160 ℃.

3. The method for drying the fine slag of the coal gas production device according to claim 1, wherein the water washing in the step 1 can be one or two of boiler feed water and ash water.

4. The method for drying the fine slag of the coal gas production device according to claim 1, wherein the solid content in the fine slag slurry in the step 2 is 5-25 wt%; the water content of the fine slag filter is 30-60 wt%; the grain size of the fine slag filter is less than or equal to 2 mm.

5. The fine slag drying method for the coal gas making device according to claim 1, wherein the fine slag filter in the step 2 can be one or more of a vacuum belt filter, a centrifuge and a plate and frame filter.

6. the fine slag drying method for the coal gas plant as claimed in claim 1, wherein the fine slag flash evaporation gas dryer in step 3 can be one or two of a rotary dryer and a tubular dryer.

7. The method for drying the fine slag of the coal gas production device according to claim 6, wherein the tubular dryer is provided with a plurality of drying tubes, helical blades are arranged in the drying tubes, the water-containing fine slag moves in the drying tubes through the action of gravity and the diversion of the helical blades, and flash steam is introduced outside the drying tubes.

8. The method for drying the fine slag of the coal gas production device according to claim 6, wherein the rotary dryer is provided with a plurality of drying pipes, the water-containing fine slag moves outside the drying pipes, and flash steam is introduced into the drying pipes.

9. The method for drying the fine slag of the coal gas production device according to claim 1, wherein the flash gas in the step 3 can be one or a combination of high-pressure flash gas and low-pressure flash gas in the step 1, and the amount of the flash gas can be part or all of the high-pressure flash gas and/or the low-pressure flash gas.

10. the method for drying the fine slag of the coal gas making device according to claim 1, wherein the water content of the fine slag dried in the step 3 is 5-15 wt%.

Technical Field

The invention belongs to the technical field of coal chemical industry, and particularly relates to a fine slag drying method for a coal gas making device.

Background

At present, because the energy reserve of China has the characteristics of 'oil shortage, gas shortage and coal existence', the application of coal in the fields of energy and chemical industry is more and more emphasized. The coal gas produced by gasifying coal as a raw material is a clean and efficient coal utilization mode. The gasification method using coal as raw material mainly includes fixed bed, fluidized bed and entrained flow bed, etc., among which entrained flow gasification furnace is the cleanest and most efficient type of coal gasification. The coal is gasified at 1200-1700 ℃, the high temperature ensures the complete gasification of the coal, and the mineral substances in the coal leave the gasification furnace after becoming slag. The entrained flow bed uses a wider range of coal than moving beds and fluidized beds. The entrained-flow bed gasification technology is widely applied to foreign technologies such as coal water slurry gasification technology of American Texaco (which belongs to GE company), Shell (Shell) powder coal pressure gasification technology of Netherlands and GSP powder coal gasification technology of German Siemens, and domestic technologies such as multi-nozzle opposed coal water slurry gasification technology of China eastern university.

In the above technology, a grey water treatment unit is required to be arranged to separate solid and liquid of black water discharged from gasification, and the method generally adopted is flash evaporation, precipitation and filtration. Flash evaporation flow in the existing production device is mainly two-stage or three-stage flash evaporation, precipitation is generally finished by using a settling tank (a clarifying tank), and fine slag filtration is generally performed by adopting vacuum bag type filtration, centrifugal filtration, plate frame type filtration and the like. The water content of the fine slag after filtration is generally 40-60 wt%, and the carbon content in the fine slag is generally 20-40 wt%. For the fine slag, there are generally two treatment methods: one is used as a blending raw material for building materials, construction, roads, backfill engineering and the like, so that combustible components of fine slag cannot be effectively utilized, and resource waste is caused; the other method is to mix the dried fine slag into a pulverized coal boiler for combustion, so that the fuel coal is saved, and the subsequent treatment capacity of the fine slag is reduced, but the water content of the fine ash is too high, and if the drying method is adopted, the occupied area is large, and the environment is polluted.

Chinese patent CN107362614 discloses a method and a device for recycling water-coal-slurry gasified fine slag, which introduces water vapor into a serpentine coil of a slope type solid material drying bed, heats the fine slag to be dried, and takes away the water contained in the fine slag through evaporation to realize the dehydration and drying treatment of the fine slag. The technical route needs to adopt water vapor as a heat source for drying the fine slag, and the energy consumption is large in the process of drying the fine slag, so that the economical efficiency of recycling the fine slag is greatly reduced.

Chinese patent CN107162102 proposes a dehydration drying method for coal gasification system fine slag slurry and a dehydration drying system used therein. According to the method, the air is heated by using the low-pressure flash steam of the coal gasification system, and the concentrated fine slag slurry is dried by using the heated hot air through a spray dehydration drying technology, so that part of waste heat of the low-pressure flash steam can be utilized, and the dried fine slag can be further utilized, and the purposes of energy conservation and emission reduction are achieved. However, the technical scheme has the following problems, which influence the further popularization and application of the technology:

(1) The low-pressure flash steam adopted by the technical scheme heats air, and the heated air is reused for drying fine slag, so that the drying process is complex, the heat loss in the process is large, and the heat efficiency is relatively low.

(2) The scheme adopts air spray drying, and the air pressurized by the air blower needs to consume certain electric energy, so that the energy consumption is relatively high.

(3) Because the heating adopts air, the wet-dried tail gas at the outlet of the spray dryer contains a large amount of air, so that the condensation load of a wet-dried tail gas condenser is high, and the exhaust emission is relatively high.

(4) The pre-dehydration concentration device is a hydrocyclone or a centrifugal filter, and the transformation of most coal gasification devices which are already in operation at present is relatively difficult.

Therefore, at present, a method for dehydrating and drying the fine slag is urgently needed to be found, so that the energy loss in the dehydration process is reduced, the purpose of recycling the combustible components in the fine slag is realized, the economic benefit of a factory is improved, and the purposes of energy conservation and emission reduction are achieved.

Disclosure of Invention

the invention aims to provide a method for drying fine slag of a coal gas making device, which fully utilizes the waste heat of high-pressure flash steam and low-pressure flash steam of the coal gas making device to further dry and utilize the fine slag, thereby not only improving the waste heat utilization rate of the coal gas making device, but also further utilizing the dried fine slag and realizing the purposes of energy conservation and emission reduction.

The invention adopts the technical scheme that a method for drying fine slag of a coal gas making device is implemented according to the following steps:

Step 1, decompressing high-temperature high-pressure solid-containing black water from a coal gas production device, and then sending the decompressed black water into a high-pressure flash evaporator, wherein part of high-pressure flash steam obtained by high-pressure flash evaporation enters a fine slag flash steam dryer, and the other part of the high-pressure flash steam is sent out of the dryer; the black water after high-pressure flash evaporation concentration enters a low-pressure flash evaporator for further flash evaporation after being decompressed; part of the low-pressure flash steam flashed from the low-pressure flash evaporator enters a fine slag flash steam dryer, and the other part of the low-pressure flash steam is sent out of the room; the black water after low-pressure flash evaporation concentration enters a vacuum flash evaporator for further flash evaporation, and vacuum flash evaporation gas is sent out;

in order to ensure the cleanliness of the high-pressure flash steam and the low-pressure flash steam, the high-pressure flash evaporator and the low-pressure flash evaporator are respectively provided with a tower tray, and dust carried in the flash steam is removed by water washing;

Step 2, the black water after vacuum flash evaporation automatically flows to a clarifying tank, the clear water on the upper part of the clarifying tank overflows and enters an ash water tank, fine slag slurry on the bottom of the clarifying tank is sent to a fine slag filter through a feeding pump, filtrate produced by the fine slag filter enters the clarifying tank, and fine slag discharged from the fine slag filter enters a fine slag flash evaporation gas dryer through a fine slag screw feeder;

Step 3, the fine slag flash evaporation gas dryer heats the fine slag and evaporates water contained in the fine slag through indirect heat exchange by utilizing the waste heat of the flash evaporation gas, so as to achieve the purpose of drying the fine slag; after the flash evaporation gas of the dried fine slag is subjected to gas-liquid separation by a flash evaporation separator, the gas phase is sent out, and the liquid phase enters an ash water tank; moisture generated in the fine slag drying process is cooled by the waste gas cooler and then enters the waste gas separator, gas phase is directly discharged to the atmosphere, condensate is returned to the grey water tank, and the dried fine slag is directly sent to the outside for utilization.

The invention is also characterized in that the method,

The pressure of the high-pressure flash steam in the step 1 is 0.6-1.5 MPaG, and the temperature is 165-205 ℃.

The pressure of the low-pressure flash steam in the step 1 is 0.1-0.5 MPaG, and the temperature is 120-160 ℃.

In the step 1, one or two of boiler feed water and ash water can be selected for washing.

in the step 2, the solid content of the fine slag slurry is 5-25 wt%.

The water content of the fine slag filter in the step 2 is 30-60 wt%; the grain size of the fine slag filter is less than or equal to 2 mm.

The fine residue filter in the step 2 can be one or a combination of a vacuum belt filter, a centrifuge and a plate frame filter.

the fine slag flash evaporation gas dryer in the step 3 can be one or the combination of a rotary dryer and a tubular dryer, wherein the tubular dryer is provided with a plurality of drying tubes, helical blades are arranged in the drying tubes, the water-containing fine slag moves in the drying tubes under the guide action of gravity and the helical blades, and the flash evaporation gas is introduced outside the drying tubes; the rotary dryer is provided with a plurality of drying tubes, the water-containing fine slag moves outside the drying tubes, and flash evaporation gas is introduced into the drying tubes.

The flash gas in the step 3 can be one or the combination of high-pressure flash gas and low-pressure flash gas in the step 1, and the flash gas amount can be part or all of the high-pressure flash gas and/or the low-pressure flash gas.

the water content of the fine slag dried in the step 3 is 5-15 wt%.

The method for drying the fine slag of the coal gas production device has the advantages that the heat of high/low pressure flash steam of a coal gasification system can be fully utilized to dry the fine slag, the drying process is relatively simple, the heat efficiency is relatively high, the energy loss in the dehydration process is low, the combustible components in the fine slag can be reused, the economic benefit of a factory is improved, and the purposes of energy conservation and emission reduction are achieved.

Drawings

FIG. 1 is a flow chart of a fine slag drying process of a coal gas making device adopted by the invention.

Detailed Description

The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

The invention relates to a fine slag drying method for a coal gas making device, which is implemented according to the following steps:

Step 1, decompressing high-temperature high-pressure solid-containing black water from a coal gas production device, and then sending the decompressed high-pressure black water into a high-pressure flash evaporator, wherein a part of high-pressure flash steam obtained by high-pressure flash evaporation enters a fine slag flash steam dryer, and the other part of the high-pressure flash steam is sent out, the pressure of the high-pressure flash steam is 0.6-1.5 MPaG, and the temperature is 165-205 ℃; the black water concentrated by high-pressure flash evaporation enters a low-pressure flash evaporator for further flash evaporation after being decompressed, wherein the pressure of low-pressure flash evaporation gas is 0.1-0.5 MPaG, and the temperature is 120-160 ℃; part of the low-pressure flash steam flashed from the low-pressure flash evaporator enters a fine slag flash steam dryer, and the other part of the low-pressure flash steam is sent out of the room; the black water after low-pressure flash evaporation concentration enters a vacuum flash evaporator for further flash evaporation, and vacuum flash evaporation gas is sent out.

In order to ensure the cleanliness of the high-pressure flash steam and the low-pressure flash steam, the high-pressure flash steam evaporator and the low-pressure flash steam evaporator are respectively provided with tower trays, and dust carried in the flash steam is removed by water washing. The water washing can be one or two of boiler feed water and ash water.

And 2, automatically flowing the black water subjected to vacuum flash evaporation to a clarifying tank, overflowing the clear water on the upper part of the clarifying tank into an ash water tank, feeding the fine slag slurry on the bottom of the clarifying tank into a fine slag filter through a feeding pump, feeding the filtrate generated by the fine slag filter into the clarifying tank, and feeding the fine slag discharged from the fine slag filter into a fine slag flash evaporation gas dryer through a fine slag screw feeder.

Controlling the solid content in the fine slag slurry to be 5-25 wt%; the water content of the fine slag filter is 30-60 wt%; the grain size of the fine slag filter is less than or equal to 2 mm.

The fine residue filter can be one or a combination of a vacuum belt filter, a centrifuge and a plate filter.

step 3, the fine slag flash evaporation gas dryer heats the fine slag and evaporates water contained in the fine slag through indirect heat exchange by utilizing the waste heat of the flash evaporation gas, so as to achieve the purpose of drying the fine slag; after the flash evaporation gas of the dried fine slag is subjected to gas-liquid separation by a flash evaporation separator, the gas phase is sent out, and the liquid phase enters an ash water tank; moisture generated in the fine slag drying process is cooled by the waste gas cooler and then enters the waste gas separator, gas phase is directly discharged to the atmosphere, condensate is returned to the grey water tank, and the dried fine slag is directly sent to the outside for utilization.

The fine slag flash evaporation gas dryer can be one or the combination of a rotary dryer and a tubular dryer, wherein the tubular dryer is provided with a plurality of drying tubes, helical blades are arranged in the drying tubes, the water-containing fine slag moves in the drying tubes under the guide action of gravity and the helical blades, and flash evaporation gas is introduced outside the drying tubes; the rotary dryer is provided with a plurality of drying tubes, the water-containing fine slag moves outside the drying tubes, and flash evaporation gas is introduced into the drying tubes.

The flash gas can be one or the combination of high-pressure flash gas and low-pressure flash gas in the step 1, and the flash gas amount can be part or all of the high-pressure flash gas and/or the low-pressure flash gas.

The water content of the dried fine slag is 5-15 wt%.

The method can fully utilize the heat of high/low pressure flash steam of the coal gasification system to dry the fine slag, has relatively simple drying process, relatively high thermal efficiency and low energy loss in the dehydration process, can realize the reutilization of combustible components in the fine slag, improves the economic benefit of a factory, and achieves the purposes of energy conservation and emission reduction.