CN212253712U - Heating furnace flue gas dehydration and heat recovery system - Google Patents
Heating furnace flue gas dehydration and heat recovery system Download PDFInfo
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- CN212253712U CN212253712U CN202021920044.3U CN202021920044U CN212253712U CN 212253712 U CN212253712 U CN 212253712U CN 202021920044 U CN202021920044 U CN 202021920044U CN 212253712 U CN212253712 U CN 212253712U
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Abstract
The utility model relates to a heating furnace technical field discloses a heating furnace flue gas dehydration and heat recovery system, the system is including consecutive heating furnace, high temperature air preheater, first low temperature air preheater, second low temperature air preheater, take off liquid water drum, draught fan and chimney to and the heat exchanger that links to each other respectively with first low temperature air preheater and second low temperature air preheater, the air-blower that links to each other with the heat exchanger, with take off liquid water drum consecutive neutralization jar and alkali lye storage tank. The utility model provides a heating furnace flue gas dehydration and heat recovery system can reduce the corruption of draught fan and chimney with the whole desorption of water in the heating furnace flue gas basically, reduces the load of draught fan, improves the thermal efficiency of heating furnace.
Description
Technical Field
The utility model relates to a heating furnace technical field, concretely relates to heating furnace flue gas dehydration and heat recovery system.
Background
In a traditional petrochemical device, a heating furnace is a device with wide application, and flue gas discharged by the heating furnace is generally conveyed to a chimney by a draught fan after heat exchange with air in an air preheater and finally discharged to the atmosphere. Because the fuel of the heating furnace contains sulfide, the flue gas discharged by the heating furnace contains a large amount of water vapor and a small amount of acid gas. Acid mist formed by combining the acid gas and water is brought into the induced draft fan by smoke gas, is extremely easy to corrode the induced draft fan, can corrode a chimney, and is directly discharged into the atmosphere to easily form acid rain to pollute the environment. In addition, because the flue gas volume that the heating furnace discharged is great, the load of draught fan is limited, often opens reserve draught fan together in the industrial production to lead to the fault-tolerant ability of heating furnace system relatively poor.
Carry out dehydration to air heater exhaust flue gas, can reduce the emission of flue gas on the one hand to reduce the draught fan load, on the other hand can detach acid gas together at the in-process of dehydration, can effectively reduce acid mist and smoke and dust content in the flue gas, reduce the corruption of draught fan and chimney, avoid acid mist to discharge into the atmosphere simultaneously, the polluted environment.
However, in practical production, the temperature of the flue gas discharged from the air preheater is generally higher, which is about 120-: 1) the smoke discharge temperature is reduced, water is condensed, and moisture in smoke is conveniently removed, but dew point corrosion of the air preheater is aggravated; 2) because the flue gas contains a large amount of water vapor, the flue gas is specially dehydrated to obtain a large amount of condensed water, and if the condensed water cannot be discharged in time, the produced accumulated water easily damages the induced draft fan, so that equipment failure is caused. In the current industrial production, the amount of water condensed in the process of discharging flue gas is generally small, most of water in the flue gas is discharged into the atmosphere along with the flue gas, and the existing condensed water discharge port is difficult to meet the requirement of large-scale dehydration of the flue gas; 3) the temperature of water that condenses down from the flue gas is high, and acidity is strong, has danger, and direct emission not only can cause the heat waste, does not accord with the environmental protection requirement moreover.
CN1793766A discloses a tubular heating furnace, including heating furnace body and waste heat recovery system, waste heat recovery system includes air heater, and wherein air heater comprises noncondensable air heater and condensing air heater two sections, is equipped with condensate collecting pit, draught fan and air-blower in the waste heat recovery system in addition, and the condensate collecting pit is directly established in condensing air heater below, and the condensate collecting pit is connected with the draught fan, and the air-blower links to each other with condensing air heater. Although the pipe-type heating furnace can recover partial latent heat of vaporization of the acid-containing water vapor and further improve the heat efficiency of the heating furnace, the exhaust gas temperature is about 100 ℃, the acid-containing water vapor in the flue gas cannot be completely condensed, and the flue gas dehydration effect still needs to be further improved. And the condensing air preheater has the inhomogeneous problem of heat transfer, local dew point corrosion appears easily, and because the inhomogeneous high exhaust gas temperature that has caused of heat transfer, the heating furnace thermal efficiency descends, and the water in the flue gas is most along with the flue gas is discharged into the atmosphere, and the water yield of condensation desorption is very few.
Therefore, it is urgently needed to provide a heating furnace flue gas dehydration and heat recovery system with good dehydration effect, small load of a draught fan, good environmental protection performance and convenient operation.
SUMMERY OF THE UTILITY MODEL
The utility model aims at overcoming the draught fan that prior art exists and corroding seriously, the load is big, and calorific loss is many, and acid flue gas corrodes the chimney, emits into the atmosphere polluted environment, and the problem that the water yield of desorption is very few in the flue gas provides a heating furnace flue gas dehydration and heat recovery system, and this system can be basically with the whole desorption of water in the heating furnace flue gas, utilizes the hot-air heating of desorption, can improve the thermal efficiency of heating furnace about 1.2%.
In order to achieve the purpose, the utility model provides a heating furnace flue gas dehydration and heat recovery system, the system comprises a heating furnace, a high temperature air preheater, a first low temperature air preheater, a second low temperature air preheater, a liquid-removing water bag, a draught fan and a chimney which are connected in sequence, a heat exchanger respectively connected with the first low temperature air preheater and the second low temperature air preheater, an air blower connected with the heat exchanger, a neutralization tank and an alkali liquor storage tank which are connected in sequence with the liquid-removing water bag;
the first low-temperature air preheater is provided with a first low-temperature air preheater high-temperature flue gas outlet and a first low-temperature air preheater low-temperature flue gas outlet; a second low-temperature air preheater high-temperature flue gas inlet and a second low-temperature air preheater low-temperature flue gas inlet are formed in the second low-temperature air preheater; the high-temperature flue gas outlet of the first low-temperature air preheater is connected with the low-temperature flue gas inlet of the second low-temperature air preheater; the low-temperature flue gas outlet of the first low-temperature air preheater is connected with the high-temperature flue gas inlet of the second low-temperature air preheater;
a first flue is arranged between the second low-temperature air preheater and the liquid removal water bag, and a second flue is arranged between the liquid removal water bag and the induced draft fan; at least one transverse baffle is arranged in the first flue, and at least one oblique baffle is arranged below the transverse baffle; at least one defoaming net is arranged in the second flue;
the neutralization tank is used for carrying out neutralization reaction on condensed water from the liquid-removing water bag and alkali liquor from the alkali liquor storage tank to obtain wastewater; the heat exchanger is used for recovering heat of waste water in the neutralization tank so as to heat air entering the first low-temperature air preheater and the second low-temperature air preheater.
Preferably, the number of the transverse baffles is two, and the two transverse baffles are staggered and distributed at intervals in the first flue along the extending direction of the first flue.
Preferably, the transverse baffle is provided with a tear hole, and the ratio of the area of the transverse baffle to the cross-sectional area of the first flue in the direction perpendicular to the extension direction of the first flue is 1: 3-4.
Preferably, the inclined baffle is arranged below the transverse baffle closest to the liquid removing water bag and above the liquid removing water bag, and an acute included angle between the inclined baffle and the transverse baffle is 30-60 degrees.
Preferably, the acute included angle between the defoaming net and the extending direction of the second flue is 30-60 degrees.
Preferably, the first flue comprises a mixing flue and a dehydration flue, wherein the mixing flue is arranged at the bottom of the second low-temperature air preheater, and wraps the high-temperature flue gas outlet of the second low-temperature air preheater and the low-temperature flue gas outlet of the second low-temperature air preheater for mixing the flue gas discharged from the high-temperature flue gas outlet of the second low-temperature air preheater and the flue gas discharged from the low-temperature flue gas outlet of the second low-temperature air preheater; the dehydration flue is arranged between the mixed flue and the liquid removal water bag, and a transverse baffle and an oblique baffle are arranged in the dehydration flue to play a role in dehydration.
Preferably, a flue with sieve holes is arranged in the mixed flue, wherein one end of the flue with the sieve holes is connected with the bottom of the second low-temperature air preheater and is positioned between the high-temperature flue gas outlet of the second low-temperature air preheater and the low-temperature flue gas outlet of the second low-temperature air preheater, and the other end of the flue with the sieve holes is connected with the inlet of the dehydration flue.
Preferably, the first low-temperature air preheater and the second low-temperature air preheater are cast iron plate type air preheaters.
Preferably, the neutralization tank is connected with the alkali liquor storage tank through an alkali liquor injection pump; an alkali liquor return pipeline is arranged between the outlet of the alkali liquor injection pump and the alkali liquor storage tank, and an alkali liquor return gate valve is arranged on the alkali liquor return pipeline.
Preferably, the system further comprises a pressure equalization line disposed between the neutralization tank and the second flue.
Through the technical scheme, the utility model discloses the beneficial technological effect who has as follows:
1) the heating furnace flue gas dehydration and heat recovery system provided by the utility model ensures that the temperature of the flue gas discharged by the second low-temperature air preheater is more uniform through the cross connection between the first low-temperature air preheater and the second low-temperature air preheater; by arranging the liquid removal water bag, the flue with the sieve holes, the transverse baffle, the inclined baffle and the defoaming net, all water and smoke dust carried in the flue gas can be safely, conveniently and quickly removed basically, so that the heat efficiency of the heating furnace is improved by about 0.4 percent;
2) the heating furnace flue gas dehydration and heat recovery system provided by the utility model realizes the pressure balance between the neutralization tank and the liquid removal water drum by arranging the pressure balance pipeline, and avoids the conditions of dehydration resistance increase, dehydration difficulty and the like caused by negative pressure;
3) the heating furnace flue gas dehydration and heat recovery system provided by the utility model can effectively observe the conditions in the liquid removal water bag and the neutralization tank by arranging the liquid level meter at one side of the liquid removal water bag and the neutralization tank, and meanwhile, the filter is arranged at the bottom of the liquid removal water bag to filter out impurities such as smoke dust and the like, so as to prevent the impurities from blocking the drainage pipeline;
4) the heating furnace flue gas dehydration and heat recovery system provided by the utility model injects alkali liquor into the neutralization tank through the alkali liquor storage tank and the alkali liquor injection pump to neutralize the acidity of water, thereby realizing safe, convenient and environment-friendly treatment of the removed condensed water;
5) the utility model discloses in the heating furnace flue gas dehydration and the heat recovery system that provide, utilize the comdenstion water heated air of desorption, can be so that the thermal efficiency of heating furnace improves about 0.8%.
Drawings
FIG. 1 is a schematic diagram of a furnace flue gas dehydration and heat recovery system;
FIG. 2 is a schematic structural view of a flue with screen holes;
FIG. 3 is a schematic structural view of a transverse baffle;
fig. 4 is a schematic view of the heating furnace system in comparative example 1.
Description of the reference numerals
1. Heating furnace 2, high temperature air preheater 31, first low temperature air preheater
32. Second low temperature air preheater 4, draught fan 5, air-blower
51. Air duct 52 at inlet of blower, air duct 6 at outlet of blower and liquid-removing water bag
61. Liquid-removing water drum liquid level meter 62, drainage gate valve 63 and filter
64. Stop valve 71, transverse baffle 72 and oblique baffle
73. Defoaming net 81, mixing flue 82 and dewatering flue
83. Flue 84 with sieve holes, inclined flue 9 and chimney
10. Neutralization tank 101, pressure balance pipeline 102 and balance gate valve
103. Glass plate liquid level meter 104, remote transmission liquid level meter 105 and pH on-line monitor
106. Sampling pipeline 107, sampling gate valve 11 and alkali liquor storage tank
111. Alkali injection funnel 112, alkali injection gate valve 113, water injection pipeline
114. Water injection gate valve 115, alkali liquor storage tank level gauge 12, alkali liquor injection pump
121. Alkali liquor regulating valve 122, alkali liquor flowmeter 123 and alkali liquor return pipeline
124. Alkali liquor return gate valve 13, heat exchanger 14 and waste water delivery pump
141. Waste water return line 142, waste water return gate valve 143, waste water outlet regulating valve
144. Waste water flowmeter 15, air suction inlet 16, sewage treatment pipeline
3. Low-temperature air preheater
Detailed Description
The utility model provides a heating furnace flue gas dehydration and heat recovery system, the system comprises a heating furnace 1, a high temperature air preheater 2, a first low temperature air preheater 31, a second low temperature air preheater 32, a liquid-removing water bag 6, a draught fan 4 and a chimney 9 which are connected in sequence, a heat exchanger 13 which is respectively connected with the first low temperature air preheater 31 and the second low temperature air preheater 32, an air blower 5 which is connected with the heat exchanger 13, a neutralization tank 10 and an alkali liquor storage tank 11 which are connected with the liquid-removing water bag 6 in sequence;
the first low-temperature air preheater 31 is provided with a first low-temperature air preheater high-temperature flue gas outlet and a first low-temperature air preheater low-temperature flue gas outlet; a second low-temperature air preheater high-temperature flue gas inlet and a second low-temperature air preheater low-temperature flue gas inlet are arranged on the second low-temperature air preheater 32; the first low-temperature air preheater high-temperature flue gas outlet is connected with the second low-temperature air preheater low-temperature flue gas inlet, and the first low-temperature air preheater low-temperature flue gas outlet is connected with the second low-temperature air preheater high-temperature flue gas inlet;
a first flue is arranged between the second low-temperature air preheater 32 and the liquid-removing water bag 6, and a second flue is arranged between the liquid-removing water bag 6 and the induced draft fan 4; at least one transverse baffle 71 is arranged in the first flue, and at least one inclined baffle 72 is arranged below the transverse baffle 71; at least one defoaming net 73 is arranged in the second flue;
the neutralization tank 10 is used for carrying out neutralization reaction on the condensed water from the liquid-removing water bag 6 and the alkali liquor from the alkali liquor storage tank 11 to obtain wastewater; the heat exchanger 13 is used for recovering heat of the wastewater in the neutralization tank 10 to heat air entering the first low-temperature air preheater 31 and the second low-temperature air preheater 32, and the specific structure of the system is shown in fig. 1.
At present, a multistage air preheater is generally utilized in industrial production to indirectly exchange heat between air and flue gas so as to reduce the temperature of flue gas, and meanwhile, the air preheater is prepared by adopting a corrosion-resistant material so as to solve the problem of dew point corrosion. The most commonly used corrosion resistant air preheaters at present are cast iron plate air preheaters. Because the heat exchange area of the cast iron plate type air preheater is larger, the temperature of the flue gas discharged from the two flue gas outlets of the cast iron plate type air preheater is uneven, one temperature is lower and is about 80 ℃, and the other temperature is higher and is about 105 ℃. The flue gas with low exhaust gas temperature causes serious dew point corrosion of a heat exchange surface near a flue gas outlet of the air preheater; moisture entrained in the flue gas with higher exhaust gas temperature exists in the form of gas, and because the flue between the air preheater and the induced draft fan is shorter, the moisture is difficult to condense and remove before the flue gas enters the induced draft fan, so that the induced draft fan and a chimney are easily corroded. In addition, the flue gas that has the difference in temperature mixes inhomogeneous also can influence the precision of exhaust gas temperature measurement, increases the regulation and control degree of difficulty of system.
The utility model discloses an inventor discovers through the research, heat transfer area at cast iron plate air heater keeps under the unchangeable circumstances, be divided into two with cast iron plate air heater, set up to two, through cross connection between two low temperature air heaters, can reduce the difference in temperature of two exhanst gas outlet exhaust flue gases of cast iron plate air heater, make the temperature of the flue gas of exhaust gas temperature low on the one side obtain improving, the temperature of the flue gas of exhaust gas temperature high on the other side obtains reducing, thereby the dew point corrosion problem that cast iron plate air heater brought because of local flue gas exhaust gas temperature low on the other side and because of the dehydration difficulty that local flue gas exhaust gas temperature high on the other side brought have been solved.
The utility model discloses in, the temperature of the flue gas of first low temperature air preheater low temperature flue gas outlet exhaust 120-; the temperature of the flue gas discharged from the low-temperature flue gas outlet of the second low-temperature air preheater is 86-94 ℃, preferably 88-92 ℃, and the temperature of the flue gas discharged from the high-temperature flue gas outlet of the second low-temperature air preheater is 88-96 ℃, preferably 90-94 ℃.
Under the condition that the heat exchange area is not changed, when only one cast iron plate type air preheater is adopted for heat exchange, the temperatures of the flue gas discharged from two flue gas outlets of the cast iron plate type air preheater are respectively about 80 ℃ and 105 ℃. After the cast iron plate type air preheaters are arranged into two, the temperature of the flue gas discharged from the two flue gas outlets of the second low-temperature air preheater 32 is between 86 and 94 ℃ and between 88 and 96 ℃. Because the temperature of the flue gas discharged from the two flue gas outlets of the second low-temperature air preheater 32 is above the dew point corrosion temperature (84 ℃), the problem of dew point corrosion of the cast iron plate type air preheater caused by low local flue gas temperature is solved. Because the temperature of the flue gas discharged from the two flue gas outlets of the second low-temperature air preheater 32 is below 99 ℃ (at this temperature, water is mainly in a liquid state, which is beneficial to separation from the flue gas), the transverse baffle 71, the oblique baffle 72 and the defoaming net 73 are arranged in the pipeline between the second low-temperature air preheater 32 and the induced draft fan 4, so that the moisture can be rapidly removed from the flue gas, the discharge amount of the flue gas is reduced, and the load of the induced draft fan 4 is reduced. The liquid-removing water bag 6 arranged in the flue can play a role in collecting condensed water and timely discharging the condensed water out of the system so as to reduce the burden of the flue.
Preferably, the high-temperature air preheater 2 is provided with a high-temperature air preheater air inlet and a high-temperature air preheater air outlet, the first low-temperature air preheater 31 is provided with a first low-temperature air preheater air inlet and a first low-temperature air preheater air outlet, and the second low-temperature air preheater 32 is provided with a second low-temperature air preheater air inlet and a second low-temperature air preheater air outlet; the first low-temperature air preheater air inlet and the second low-temperature air preheater air inlet are respectively connected with the air blower outlet air duct 52, the first low-temperature air preheater air outlet and the second low-temperature air preheater air outlet are respectively connected with the high-temperature air preheater air inlet, and the high-temperature air preheater air outlet is connected with the heating furnace air inlet.
Preferably, the high-temperature air preheater 2 is further provided with a high-temperature air preheater flue gas inlet and a high-temperature air preheater flue gas outlet, and the first low-temperature air preheater 31 is further provided with a first low-temperature air preheater high-temperature flue gas inlet connected with the first low-temperature air preheater high-temperature flue gas outlet and a first low-temperature air preheater low-temperature flue gas inlet connected with the first low-temperature air preheater low-temperature flue gas outlet; the second low-temperature air preheater 32 is also provided with a second low-temperature air preheater high-temperature flue gas outlet connected with the second low-temperature air preheater high-temperature flue gas inlet and a second low-temperature air preheater low-temperature flue gas outlet connected with the second low-temperature air preheater low-temperature flue gas inlet; wherein, high temperature air preheater flue gas entry links to each other with the heating furnace exhanst gas outlet, high temperature air preheater exhanst gas outlet links to each other with first low temperature air preheater high temperature flue gas entry and first low temperature air preheater low temperature flue gas entry respectively, second low temperature air preheater high temperature flue gas outlet and second low temperature air preheater low temperature exhanst gas outlet link to each other with draught fan 4.
In the present invention, the first low-temperature air preheater 31 is taken as an example to explain the high/low-temperature inlet/outlet: and the smoke outlet/inlet arranged on one side close to the air inlet of the first low-temperature air pre-heater is the low-temperature smoke outlet/inlet of the first low-temperature air pre-heater, and on the contrary, the smoke outlet/inlet arranged on one side close to the air outlet of the first low-temperature air pre-heater is the high-temperature smoke outlet/inlet of the first low-temperature air pre-heater. The amount of the flue gas discharged from the flue gas outlet of the high-temperature air preheater entering the high-temperature flue gas inlet of the first low-temperature air preheater is preferably equal to the amount of the flue gas discharged from the flue gas outlet of the first low-temperature air preheater entering the low-temperature flue gas inlet of the first low-temperature air preheater. The amount of air discharged from the blower 5 entering the first low temperature air pre-heater air inlet and the amount of air entering the second low temperature air pre-heater air inlet are preferably equal.
Preferably, the first flue comprises a mixing flue 81 and a dewatering flue 82, wherein the pipe diameter of the mixing flue 81 is larger than that of the dewatering flue 82; wherein, the utility model discloses do not specially limit to the shape of first flue, the flue is preferably rectangle or square. The mixing flue 81 is arranged at the bottom of the second low-temperature air preheater 32, wraps the high-temperature flue gas outlet of the second low-temperature air preheater and the low-temperature flue gas outlet of the second low-temperature air preheater, and is used for mixing flue gas discharged from the high-temperature flue gas outlet of the second low-temperature air preheater and the low-temperature flue gas outlet of the second low-temperature air preheater; the dehydration flue 82 is arranged between the mixing flue 81 and the liquid removal water bag 6, and the dehydration flue 82 is internally provided with the transverse baffle 71 and the oblique baffle 72 to play a role in dehydration. In the present invention, the joint between the dehydration flue 82 and the mixing flue 81 is referred to as the inlet of the dehydration flue 82.
Preferably, in order to improve the mixing effect of the flue gas, a flue 83 with a sieve hole is arranged in the mixing flue 81, as shown in fig. 2. One end of the flue 83 with the sieve holes is connected with the bottom of the second low-temperature air preheater 32, and is located between the high-temperature flue gas outlet of the second low-temperature air preheater and the low-temperature flue gas outlet of the second low-temperature air preheater, and the other end is connected with the inlet of the dehydration flue 82. Wherein, the flue 83 with sieve holes can change the flowing direction of the flue gas, so that the temperature of the flue gas exhausted from the two smoke outlets is more uniform.
Preferably, the flue 83 with the sieve holes is a circular flue, the opening direction of the sieve holes is perpendicular to the outer surface of the flue 83 with the sieve holes, and the shape is preferably circular.
Preferably, the sieve holes are uniformly distributed along the circumferential direction of the flue 83 with the sieve holes, the aperture of the sieve holes is gradually reduced from top to bottom along the axial direction of the flue 83 with the sieve holes, the maximum aperture of the sieve holes at the upper part is about 15-30mm, and the minimum aperture of the sieve holes at the lower part is about 10-18 mm. The upper portion is an end connected to the bottom of the second low temperature air preheater 32.
The utility model discloses in, the temperature of the flue gas that obtains after the flue gas that is taken the sieve mesh from second low temperature air preheater high temperature exhanst gas outlet and second low temperature air preheater low temperature exhanst gas outlet exhaust mixes is 87-95 ℃, preferably 90-92 ℃. Because the temperature of the flue gas discharged from the second low-temperature air preheater 32 is lower than 99 ℃, water in the flue gas exists in a liquid state, and a transverse baffle 71, an oblique baffle 72 and a defoaming net 73 are arranged in a flue of the second low-temperature air preheater 32 connected with the induced draft fan 4, so that water drops carried in the flue gas can be basically and completely removed.
Preferably, the number of the transverse baffles 71 is two, and the two transverse baffles 71 are staggered and distributed at intervals in the first flue in the extending direction of the first flue. Specifically, two transverse baffles 71 are respectively disposed on the left and right sides of the dehydration flue 82, and are arranged at intervals along the extending direction of the dehydration flue 82, as shown in fig. 1. Wherein, the transverse baffle 71 is perpendicular to the extending direction of the dehydration flue 82, and is used for changing the flowing direction of the flue gas and increasing the flowing speed of the flue gas.
Preferably, the transverse baffle 71 is connected to the first flue by welding. In order to prevent the acid condensate water accumulated on the transverse baffle 71 from corroding the welding seam and reduce the connection strength between the transverse baffle 71 and the flue, and further damage the transverse baffle 71, preferably, a tear hole is arranged on the transverse baffle 71, wherein the tear hole is arranged on one side of the transverse baffle 71 connected with the flue, and preferably, 4-6 round holes with the diameter of 10-20mm are arranged, as shown in fig. 3. In order to reduce the friction between the fumes and the transverse baffles 71, it is preferable that on the transverse baffles 71, a polytetrafluoroethylene coating is provided.
Preferably, in the direction perpendicular to the extension of the first chimney, the ratio of the area of the transverse baffle 71 to the cross-sectional area of the first chimney is 1: 3-4, preferably 1: 4. wherein, the larger the ratio of the area of the transverse baffle 71 to the cross-sectional area of the first flue, the larger the change of the flow velocity of the flue gas. In order to reduce the impact force of the flue gas on the transverse baffle 71 and prolong the service life of the transverse baffle 71, the ratio of the area of the transverse baffle 71 to the cross-sectional area of the first flue is preferably limited to 1: 3-4.
The utility model discloses in through setting up polylith transverse baffle 71, preferably set up two transverse baffle 71, further preferably, the area of second piece transverse baffle 71 is big than first transverse baffle 71's area. The second transverse baffle 71 is the transverse baffle 71 closest to the liquid-removing water bag 6, so that the flow speed of the flue gas can be gradually increased, and the higher the flow speed is, the better the dehydration effect is when the flue gas collides with the inclined baffle 72.
Preferably, the inclined baffle 72 is arranged below the transverse baffle 71 closest to the liquid removing water bag 6 and above the liquid removing water bag 6, and an acute included angle between the inclined baffle 72 and the transverse baffle 71 is 30-60 degrees, preferably 45-60 degrees.
The utility model discloses in, the flue gas takes place to contact the back with transverse baffle 71, and certain change can take place for the flow direction of flue gas, makes the flue gas flow direction become "S" type, sets up oblique baffle 72 below transverse baffle 71, can make the flue gas that flow direction changes bump into oblique baffle 72 on nearly perpendicularly. After the flue gas collides with the transverse baffle 71, the gravity of the solid impurities such as water drops, smoke dust and the like is far greater than that of the flue gas, so that the solid impurities such as water drops, smoke dust and the like carried in the flue gas can be removed after the collision. The water removed from the inclined baffle 72 can clean the flue gas in the falling process, so that the smoke dust, sulfide, carbon dioxide and other substances in the flue gas are dissolved in the water as much as possible, and the aim of purifying the flue gas is fulfilled.
Preferably, in order to improve the dewatering effect, the inclined baffles 72 are arranged into 2-5 pieces, and a plurality of inclined baffles 72 are arranged in parallel; to reduce the flow resistance of the water, a teflon coating is preferably provided on the inclined baffle 72.
The water removed from the inclined baffle 72 can also re-entrain a portion of the water in the flue gas during the "cleaning" of the flue gas. In order to avoid that water carried in the flue gas corrodes the induced draft fan 4 and the chimney 9, the inventor arranges a defoaming net 73 in the second flue to remove the water in the flue gas again.
Preferably, the angle between the demister screen 73 and the extension direction of the second flue is 30-60 °, preferably 45-60 °. The acute angle included angle between the lower end of the defoaming net 73 and the extending direction of the second flue refers to the acute angle included angle between the lower end of the defoaming net 73 and the extending direction of the second flue. The defoaming net 73 is used for intercepting water drops carried in the flue gas, the intercepted water drops form large liquid drops under the action of capillary action and gravity, and the large liquid drops flow into the liquid-removing water drum 6, so that the corrosion of the induced draft fan 4 and the chimney 9 caused by the acidic water drops carried in the flue gas can be avoided, and the environment is polluted.
Preferably, the number of the defoaming net 73 is set to 1.
In order to collect the condensed water removed from the flue conveniently, the liquid-removing water drum 6 is preferably arranged at the lowest point of the flue between the second low-temperature air preheater 32 and the induced draft fan 4.
Since the defoaming net 73 is located higher than the liquid removing water drum 6, in order to allow the water intercepted by the defoaming net 73 to smoothly flow into the liquid removing water drum 6, it is preferable that an inclined flue 84 is provided between the defoaming net 73 farthest from the liquid removing water drum 6 and the liquid removing water drum 6.
Preferably, the flue gas flows through the defoaming net 73, then enters the induced draft fan 4, and finally is discharged into the chimney 9, and the flue gas is discharged into the atmosphere through the chimney 9. Wherein, the utility model discloses a flue 83, horizontal baffle 71, slant baffle 72 and the quadruple setting of defoaming net 73 of taking the sieve mesh for behind the defoaming net 73 was flowed through to the flue gas, the content of aqueous water in the flue gas is less than 2-10 wt%, and preferably is less than 3-6 wt%, can be basically all desorption with the water of smuggleing secretly in the flue gas, thereby makes the flow of flue gas can reduce 37300 and add one's charge 38500m3And h, further reducing the load of the induced draft fan 4.
Since the amount of the removed condensed water is relatively large, it is preferable that a dewatering amount is observed by a dewatering drum level meter 61 provided on the dewatering drum 6. The liquid removing water bag liquid level meter 61 is used for observing the liquid level in the liquid removing water bag 6, and the problem that water accumulated at the bottom of the air preheater cannot be checked in the prior art can be solved.
In the current industrial production, the moisture in the flue gas is not specially removed, but the condensed water accumulated at the bottom of the air preheater is discharged. However, the utility model discloses a cross connection between first low temperature air preheater 31 and the second low temperature air preheater 32 and take flue 83, transverse baffle 71, slant baffle 72 and the setting of defoaming net 73 of sieve mesh, can basically take off the water droplet that smugglies secretly in the flue gas is whole to reduce draught fan 4's load, improve the fault-tolerant ability of heating furnace system. The condensed water removed from the flue gas is not only large in quantity, but also high in temperature, generally about 80 ℃. The air entering the first low-temperature air preheater 31 and the second low-temperature air preheater 32 is heated by the water, so that not only can the heat be recovered to improve the heat efficiency of the heating furnace, but also the temperature of the air entering the first low-temperature air preheater 31 and the second low-temperature air preheater 32 can be increased, and the occurrence of local dew point corrosion is further avoided.
Because the removed condensate water contains sulfide and the pH value is usually about 3, before recovering the heat of the condensate water, the condensate water needs to be neutralized to avoid corrosion of equipment by acidic condensate water. Therefore, the system also comprises a neutralization tank 10 and an alkali liquor storage tank 11 which are sequentially connected with the liquid removing water bag 6, wherein the neutralization tank 10 is used for carrying out neutralization reaction on the condensed water from the liquid removing water bag 6 and the alkali liquor from the alkali liquor storage tank 11 to obtain the wastewater.
Preferably, a drain gate valve 62, a filter 63 and a stop valve 64 are sequentially provided on a pipeline connecting the dewatering drum 6 and the neutralization tank 10. When the level meter 61 of the dewatering drum observes that a certain amount of the condensed water flows into the dewatering drum 6, the drain gate valve 62 and the stop valve 64 can be opened to allow the condensed water collected in the dewatering drum 6 to flow into the neutralization tank 10. The filter 63 is preferably a Y-type filter, which can filter out solid impurities such as soot and the like in the liquid-removing water bag 6, and in practical application, the filter 63 can be cleaned periodically.
Since the bottom of the second low-temperature air preheater 32 is a negative pressure environment, in order to reduce the resistance of the water in the liquid removing water bag 6 flowing into the neutralization tank 10, the system preferably further comprises a pressure balance line 101, wherein the pressure balance line 101 is arranged between the neutralization tank 10 and the second flue, and a balance gate valve 102 is arranged on the pressure balance line 101.
The pressure balance pipeline 101 is used for balancing the pressure of the neutralization tank 10, during the operation of the system, the pressure balance pipeline 101 is in a normally open state, when the liquid-removing water bag 6 observes that the liquid-removing condition of the water bag is poor through the liquid-removing water bag liquid level meter 61, whether the pressure balance pipeline 101 is opened or not needs to be checked, or the filter 63 needs to be cleaned in time.
Preferably, a glass plate liquid level meter 103 and a remote transmission liquid level meter 104 are further arranged on the neutralization tank 10, wherein the glass plate liquid level meter 103 is used for observing the liquid level in the neutralization tank 10 on site, and the remote transmission liquid level meter 104 is used for transmitting a liquid level signal in the neutralization tank 10 to a DCS picture of a central control room to remotely control the liquid level in the neutralization tank 10.
In order to control the addition amount of the alkali liquor, preferably, an online pH monitor 105 and a sampling line 106 are further disposed on the neutralization tank 10, and a sampling gate valve 107 is disposed on the sampling line 106. Wherein, the pH on-line monitor 105 can transmit the pH signal in the neutralization tank 10 to a DCS picture of a central control room for remotely observing and controlling the pH value of the water in the neutralization tank 10. The sampling line 106 is used to collect and neutralize samples within the tank 10 for assay analysis.
Preferably, the neutralization tank 10 and the alkali liquor storage tank 11 are connected through an alkali liquor injection pump 12, and an alkali liquor regulating valve 121 and an alkali liquor flow meter 122 are arranged on a pipeline connecting the neutralization tank 10 and the alkali liquor injection pump 12. An alkali liquor return pipeline 123 is arranged between the outlet of the alkali liquor injection pump 12 and the alkali liquor storage tank 11, and an alkali liquor return gate valve 124 is arranged on the alkali liquor return pipeline 123. The purpose of the arrangement is to accurately control the injection amount of the alkali liquor so as to regulate and control the whole neutralization process.
In order to facilitate the addition of alkali to the lye storage tank 11, preferably, an alkali injection funnel 111 and an alkali injection gate valve 112 are provided at an upper portion of the lye storage tank 11. Wherein the alkali injection funnel 111 and the alkali injection gate valve 112 are used for injecting the alkali liquor with high concentration into the alkali liquor storage tank 11.
In order to facilitate the water injection into the lye storage tank 11, it is preferable that a water injection line 113 is further provided on the lye storage tank 11, a water injection gate valve 114 is provided on the water injection line 113, and the concentration of the lye can be adjusted through the water injection line 113.
In order to facilitate the control of the liquid level in the lye storage tank 11, preferably, a lye storage tank level gauge 115 is further provided on said lye storage tank 11.
The utility model discloses in, the temperature of the waste water that obtains after alkali lye treatment is about 80 ℃, for this part of heat of make full use of, the system still includes heat exchanger 13 and waste water delivery pump 14, wherein, heat exchanger 13 sets up in the exit of air-blower 5 for the heat of waste water gets into the air of first low temperature air preheater 31 and second low temperature air preheater 32 with the heating in retrieving neutralization tank 10 in, waste water delivery pump 14 is arranged in carrying the waste water in neutralization tank 10 in heat exchanger 13.
Preferably, between the outlet of the waste water transfer pump 14 and the neutralization tank 10, a waste water return line 141 is provided, and a waste water return gate valve 142 is provided on the waste water return line 141. Wherein the waste water return line 141 is used to control the liquid level of the neutralization tank 10 to be not less than 30% to prevent air from entering; and the disturbance of the liquid in the tank can be increased, so that the liquid in the tank is mixed more uniformly. The waste water return gate valve 142 is used to adjust the amount of waste water returned.
Preferably, a waste water outlet regulating valve 143 and a waste water flow meter 144 are provided on a pipeline connecting the waste water transfer pump 14 and the heat exchanger 13.
The utility model discloses in, the air gets into air-blower entry wind channel 51 through air inlet scoop 15, later gets into air-blower 5, and the air that comes out from air-blower 5 carries out the heat transfer with the waste water that comes from neutralization tank 10 in heat exchanger 13. After heat exchange, air discharged from the heat exchanger 13 enters the flue gas dehydration and heat recovery system through the air inlet of the first low-temperature air preheater and the air inlet of the second low-temperature air preheater respectively through the air outlet duct 52 of the blower, and wastewater discharged from the heat exchanger 13 is conveyed to the sewage treatment system through the sewage treatment pipeline 16.
The present invention will be described in detail below by way of examples. Wherein, the sum of the heat exchange areas of the first low-temperature air preheater and the second low-temperature air preheater in the embodiment 1 is equal to the heat exchange area of the low-temperature air preheater 3 in the comparative example 1. The flue gas at the outlet of the convection section of the heating furnace is also directly discharged from the flue gas outlet of the heating furnace.
Example 1
The operation was carried out according to a flue gas dehydration system as shown in FIG. 1, in which the amount of furnace fuel gas used was 10645m3The temperature of the flue gas at the outlet of the convection section of the heating furnace is 280 ℃, and the flow rate is 158300m3The water content was 24 wt.%. The temperature of the flue gas from the high-temperature air preheater is 170 ℃, and the flue gas is divided into two paths to enter the first low-temperature air preheater. The temperature of the smoke discharged from the low-temperature smoke outlet of the first low-temperature air preheater is 125 ℃, and the temperature of the smoke discharged from the high-temperature smoke outlet of the first low-temperature air preheater is 138 ℃; the temperature of the smoke discharged from the low-temperature smoke outlet of the second low-temperature air preheater is 89 ℃, and the temperature of the smoke discharged from the high-temperature smoke outlet of the second low-temperature air preheater is 91 ℃; the temperature of the mixed flue gas was 90 ℃ and the water content in the flue gas discharged from the chimney was 4 wt%.
The temperature of air sucked by the air suction inlet of the blower is 33 ℃, and the flow rate is 16900 m3H, after the air is subjected to heat exchange through the heat exchangerThe temperature of the air preheater is 36 ℃, the temperature of the air preheater is 102 ℃, the temperature of the air preheater is 142 ℃, and the temperature of the air preheater is 262 ℃.
The amount of condensed water collected in the liquid removing water bag is 32t/h, and the temperature is 90 ℃; the flow rate of the condensed water flowing into the neutralization tank is 32t/h, the amount of the injected alkali liquor is 2t/h, and the temperature of the wastewater obtained after the neutralization by adding the alkali liquor is 80 ℃. The flow rate of the wastewater conveyed into the heat exchanger is 34t/h, the temperature of the wastewater entering the heat exchanger is 80 ℃, and the temperature after heat exchange is 40 ℃.
As can be seen from the calculation, in example 1, the load of the induced draft fan is 56%, the energy consumption of the heating furnace is 210kgEO/t, and the thermal efficiency is 95.5%.
Comparative example 1
Operation was carried out according to a flue gas dehydration system as shown in FIG. 4, in which the amount of furnace fuel gas used was 11000m3The temperature of the flue gas at the outlet of the convection section of the heating furnace is 280 ℃, and the flow rate is 196200m3The water content was 24 wt.%. The temperature from the high-temperature air preheater is 170 ℃, the temperature from the low-temperature smoke outlet of the low-temperature air preheater is 80 ℃, and the temperature from the high-temperature smoke outlet of the low-temperature air preheater is 105 ℃; the temperature of the mixed flue gas is 100 ℃, and the water content in the flue gas discharged from a chimney is 20 wt%.
The temperature of air blown by the blower is 33 ℃, and the flow rate is 176000m3And h, the temperature of the high-temperature air preheater is 260 ℃, and the temperature of the low-temperature air preheater is 120 ℃. The amount of condensed water discharged from the bottom of the low-temperature air preheater was 3 t/h.
According to calculation, in the comparative example 1, the load of the induced draft fan is 68%, the energy consumption of the heating furnace is 212.6kgEO/t, and the thermal efficiency is 94.3%.
Can know through comparative example 1 and comparative example 1, the utility model provides a heating furnace flue gas dehydration and heat recovery system not only can reduce the draught fan and corrode, reduces the draught fan load, can improve the thermal efficiency of heating furnace 1.2% moreover.
The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. In the technical idea scope of the present invention, it can be right to the technical solution of the present invention perform multiple simple modifications, including each technical feature combined in any other suitable manner, these simple modifications and combinations should be regarded as the disclosed content of the present invention, and all belong to the protection scope of the present invention.
Claims (10)
1. A heating furnace flue gas dehydration and heat recovery system is characterized by comprising a heating furnace, a high-temperature air preheater, a first low-temperature air preheater, a second low-temperature air preheater, a liquid removal water drum, an induced draft fan and a chimney which are sequentially connected, heat exchangers respectively connected with the first low-temperature air preheater and the second low-temperature air preheater, an air blower connected with the heat exchangers, a neutralization tank and an alkali liquor storage tank which are sequentially connected with the liquid removal water drum;
the first low-temperature air preheater is provided with a first low-temperature air preheater high-temperature flue gas outlet and a first low-temperature air preheater low-temperature flue gas outlet; a second low-temperature air preheater high-temperature flue gas inlet and a second low-temperature air preheater low-temperature flue gas inlet are formed in the second low-temperature air preheater; the high-temperature flue gas outlet of the first low-temperature air preheater is connected with the low-temperature flue gas inlet of the second low-temperature air preheater; the low-temperature flue gas outlet of the first low-temperature air preheater is connected with the high-temperature flue gas inlet of the second low-temperature air preheater;
a first flue is arranged between the second low-temperature air preheater and the liquid removal water bag, and a second flue is arranged between the liquid removal water bag and the induced draft fan; at least one transverse baffle is arranged in the first flue, and at least one oblique baffle is arranged below the transverse baffle; at least one defoaming net is arranged in the second flue;
the neutralization tank is used for carrying out neutralization reaction on condensed water from the liquid-removing water bag and alkali liquor from the alkali liquor storage tank to obtain wastewater; the heat exchanger is used for recovering heat of waste water in the neutralization tank so as to heat air entering the first low-temperature air preheater and the second low-temperature air preheater.
2. The system of claim 1, wherein the transverse baffles are arranged in two, and the two transverse baffles are staggered and spaced apart in the first flue in the direction of extension of the first flue.
3. The system of claim 2 wherein the transverse baffle is provided with a tear hole, and wherein the ratio of the transverse baffle area to the first flue cross-sectional area, in a direction perpendicular to the first flue extension, is 1: 3-4.
4. The system of claim 2, wherein the inclined baffle is disposed below the transverse baffle closest to the dewatering drum and above the dewatering drum, and the acute angle between the inclined baffle and the transverse baffle is 30-60 °.
5. The system of claim 1, wherein the angle between the demister screen and the direction of extension of the second flue is 30-60 °.
6. The system according to claim 1, wherein the first flue comprises a mixing flue and a dehydration flue, wherein the mixing flue is arranged at the bottom of the second low-temperature air pre-heater and wraps the high-temperature flue gas outlet of the second low-temperature air pre-heater and the low-temperature flue gas outlet of the second low-temperature air pre-heater for mixing the flue gas discharged from the high-temperature flue gas outlet of the second low-temperature air pre-heater and the low-temperature flue gas outlet of the second low-temperature air pre-heater; the dehydration flue is arranged between the mixed flue and the liquid removal water bag, and a transverse baffle and an oblique baffle are arranged in the dehydration flue to play a role in dehydration.
7. The system as claimed in claim 6, wherein a flue with sieve holes is arranged in the mixing flue, wherein one end of the flue with sieve holes is connected with the bottom of the second low-temperature air preheater and is positioned between the high-temperature flue gas outlet of the second low-temperature air preheater and the low-temperature flue gas outlet of the second low-temperature air preheater, and the other end of the flue with sieve holes is connected with the inlet of the dehydration flue.
8. The system of claim 1, wherein the first and second low temperature air preheaters are cast iron plate air preheaters.
9. The system of claim 1, wherein the neutralization tank and the lye storage tank are connected by a lye injection pump; an alkali liquor return pipeline is arranged between the outlet of the alkali liquor injection pump and the alkali liquor storage tank, and an alkali liquor return gate valve is arranged on the alkali liquor return pipeline.
10. The system of claim 1, further comprising a pressure equalization line disposed between the neutralization tank and the second flue.
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| CN202021920044.3U CN212253712U (en) | 2020-09-02 | 2020-09-02 | Heating furnace flue gas dehydration and heat recovery system |
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| CN202021920044.3U CN212253712U (en) | 2020-09-02 | 2020-09-02 | Heating furnace flue gas dehydration and heat recovery system |
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