Device and method for drying, absorbing and efficiently recovering waste heat in process of preparing sulfuric acid from sulfur

Abstract

The invention discloses a device and a method for drying, absorbing and efficiently recovering waste heat in the process of preparing sulfuric acid from sulfur, and belongs to the field of waste heat recovery in the process of preparing sulfuric acid from sulfur The device and the method are characterized in that desalted water acid coolers are arranged in a drying circulating system and a secondary SO3 circulating absorption system for preparing sulfuric acid from sulfur, and waste heat in the process is recovered; the heated desalted water (or condensed water) generates more low-low pressure steam with the pressure of 0.2 + / -0.1 MPa in a serial acid waste heat recovery unit of the first SO3 circulation absorption system, and then the generated low-low pressure steam is sprayed into primary conversion process gas containing SO3 entering an inlet of a first absorption tower, so that an evaporator of the first SO3 circulation absorption system generates equal low-pressure saturated steam with the pressure of 0.8 + / -0.4 MPa (g); and meanwhile, the waste heat recovery system deaerator does not need to consume low-pressure steam, so that the net steam production rate of per ton of sulfuric acid prepared from sulfur reaches 0.6 ton of low-pressure steam per ton of acid, and the net steam production rate of per ton of acid is greatly improved compared with 0.3 ton of low-pressure steam per ton of acid in the prior art.

Description

Technical Field

[0001] The invention relates to the field of chemical industry, and in particular to the field of waste heat recovery in a sulfuric acid production process using sulfur. Background Art

[0002] Modern sulfuric acid production processes mostly use a production process of double conversion and double absorption. First, the air is sent to an air drying tower, and the sulfuric acid sprayed in the tower is used to circulate and absorb the moisture in the air. The dried air is sent to the sulfur incinerator, and the oxygen in the air reacts with sulfur as an oxidant to generate SO2. The process gas containing SO2 and O2 (temperature is about 1000℃) from the sulfur incinerator is recovered by the medium and high temperature waste heat recovery system to produce medium and high steam. After the process gas temperature is reduced, it is sent to the conversion section, where a conversion is carried out to react most of the SO2 with O2 and oxidize to generate SO3. After the first conversion, the process gas containing SO3 (the temperature is below 200℃) is sent to the first absorption tower, and the sulfuric acid sprayed in the tower is used to circulate and absorb the SO3 in the process gas. More than 99% of the SO3 in the process gas is absorbed by the acid sprayed in the first absorption tower. After the process gas leaves the first absorption tower, it returns to the conversion section for secondary conversion. The remaining SO2 continues to be oxidized to produce SO3. After the secondary conversion, the process gas is sent to the second absorption tower and the sulfuric acid sprayed in the tower is used to cycle and absorb the secondary conversion to produce SO3. After the above two conversion and two absorption processes, more than 99.9% of the SO2 produced by the sulfur incinerator is converted into SO3 and absorbed to produce sulfuric acid.

[0003] In the above sulfuric acid production process, three sulfuric acid circulation absorption systems are involved, namely:

[0004] 1) Air drying circulation system

[0005] The existing sulfur-to-sulfuric acid process technology requires that the dried air be sent to the sulfur incinerator to ensure the normal oxidation reaction in the conversion process. The way to dry the air is to send the air into an air drying tower, and use the tower to spray sulfuric acid to circulate and absorb the moisture in the air. The sulfuric acid concentration decreases during the moisture absorption process, releasing the dilution reaction heat, which accounts for about 10% of the absorption and dilution reaction heat in the entire sulfuric acid production process.

[0006] The air drying circulation system usually consists of an air drying tower, an air drying circulation pump tank, an air drying acid circulation pump, and an air drying circulation water acid cooler. The sprayed sulfuric acid in the air drying tower is sprayed from the upper part to absorb the moisture in the air sent from the lower part, and the sulfuric acid concentration is reduced. Since the dilution of sulfuric acid is an exothermic reaction, the temperature of sulfuric acid increases after leaving the air drying tower, and the sulfuric acid out of the tower enters the air drying circulation pump tank. In addition, a part of the sulfuric acid with a higher concentration in the first circulation system is also sent to the air drying circulation pump tank to increase the sulfuric acid concentration in the circulation tank. In this process, the concentration of sulfuric acid sent in is reduced, and the acid temperature in the circulation tank rises again. Then the sulfuric acid enters the air drying acid circulation pump, and is pressurized by the pump and sent to the air drying circulation water acid cooler. After cooling, most of the sulfuric acid enters the air drying tower to circulate and absorb moisture in the air, and a small part of the excess sulfuric acid returns to the first SO3 circulation absorption system, or returns to the second absorption cycle, or is sent to the acid warehouse as a finished acid.

[0007] In order to ensure that the sulfuric acid temperature in the air drying circulation system is stable within a certain range, the existing technology uses circulating water and circulating sulfuric acid in the air drying circulation system to exchange heat, remove the heat of sulfuric acid dilution reaction, and finally dissipate it into the atmosphere in the form of water evaporation in the circulating water station. This part of heat is not effectively recovered.

[0008] 2) Second SO3 cycle absorption system

[0009] In the sulfuric acid production process, the secondary conversion process gas enters the second absorption tower and the absorption process heat accounts for about 20% of the total sulfuric acid absorption and dilution reaction heat.

[0010] The second SO3 circulation absorption system usually consists of a second absorption tower, a second absorption circulation pump tank, a second absorption acid circulation pump, and a second absorption circulation water acid cooler. In the second absorption tower, sulfuric acid is sprayed from the upper part to absorb the SO3 in the secondary conversion process gas sent to the lower part. The sulfuric acid concentration increases, and the absorption reaction heat causes the sulfuric acid temperature to increase. After leaving the second absorption tower, the sulfuric acid enters the second absorption circulation pump tank. The low-concentration acid or dilution water sent by the air drying circulation system is added to the circulation tank, and mixed with the string acid sent to the first SO3 circulation absorption system. The sulfuric acid concentration returns to the concentration level of the spray acid entering the upper part of the second absorption tower, but the reaction heat released during the sulfuric acid dilution process causes the sulfuric acid temperature in the second absorption circulation pump tank to rise again. The sulfuric acid in the pump tank is pressurized by the second absorption acid circulation pump and sent to the second absorption circulation water acid cooler. After being cooled by circulating water, most of it returns to the spray acid inlet at the upper part of the second absorption tower to circulate and absorb the SO3 in the secondary conversion process gas. The excess sulfuric acid in the second SO3 circulation absorption system is sent to the air drying circulation system or sent to the acid storage as finished sulfuric acid.

[0011] In the above-mentioned second SO3 circulation absorption system of the prior art, the absorption reaction heat of SO3 and the sulfuric acid dilution reaction heat are both taken out by the circulating water in the second absorption circulation water acid cooler and finally dissipated into the atmosphere. This part of heat is also not effectively recovered.

[0012] 3) The first SO3 cycle absorption system

[0013] Since the heat of the primary conversion process gas sent out from the conversion section enters the first absorption tower to absorb the process, which accounts for more than 70% of the heat of the entire sulfuric acid absorption and dilution reaction, the newly built sulfuric acid production plants from sulfur in recent years mostly adopt high-temperature absorption processes, recovering most of the heat of the primary absorption reaction to generate low-pressure saturated steam. In such sulfuric acid plants, the first SO3 circulation absorption system usually consists of the following equipment: the first absorption tower, the first absorption acid circulation tank, the first absorption acid circulation acid pump, the evaporator, the mixer, and the acid series heat exchanger.

[0014] The process of the first SO3 cycle absorption system is as follows:

[0015] The primary conversion process gas enters the first absorption tower, where high-temperature sulfuric acid (usually around 180°C) absorbs the SO in the process gas. 3， The acid temperature and acid concentration both increase. After the temperature is increased, the concentrated sulfuric acid enters the first absorption acid circulation tank, and is then pressurized by the first absorption acid circulation acid pump and sent to the evaporator. In the evaporator, the high-temperature concentrated sulfuric acid is heated by the feed water in the evaporator to produce low-pressure steam. After the acid temperature is reduced, most of it enters the mixer to add water to reduce the acid concentration, and then is sent to the high-temperature absorption tower for circulation to absorb SO3; the other part of the excess sulfuric acid in the first SO3 circulation absorption system enters the evaporator feed water and other process materials through the serial acid heat exchanger heater, and the acid temperature is reduced to below 120°C, and is sent to the air drying circulation system and the second SO3 circulation absorption system.

[0016] In the above-mentioned first SO3 circulation absorption system, the absorption reaction heat can increase the temperature of sulfuric acid to about 200°C, and produce low-pressure saturated steam in the evaporator. Such a process system is called a low-temperature waste heat recovery system. The existing low-temperature waste heat recovery system can produce up to 0.5t of low-pressure steam (0.8MPa(g)) for every ton of sulfuric acid produced. However, in the above-mentioned low-temperature waste heat recovery system, although the excess sulfuric acid in the first SO3 circulation absorption system is sent out through the acid heat exchanger to recover part of the heat, the temperature of the sent acid is still high. This part of the acid brings out heat and enters the air drying circulation system and the second SO3 circulation absorption system. The heat is dissipated into the atmosphere through the circulating water coolers of these two systems. This part of the heat of the sent acid is still not fully and effectively recovered.

[0017] In the prior art, both the high-temperature waste heat recovery system and the low-temperature waste heat recovery system recover the waste heat from the sulfur-to-sulfuric acid process to produce steam, which requires the introduction of desalted water (or condensed water) from the outside and the thermal deoxygenation of the deaerator before supplying the waste heat recovery system. When normal temperature desalted water (or condensed water) is used to feed the deaerator, about 0.8 MPa (g) of low-pressure steam is consumed for heating water and thermal deoxygenation for every ton of sulfuric acid produced. When the steam consumption of the above-mentioned deaerator is taken into account, the net output of low-pressure steam in the prior art sulfur-to-sulfuric acid device can only reach 0.35t of 0.8 MPa (g) of low-pressure steam as a by-product for every ton of sulfuric acid produced. Summary of the invention

[0018] The present invention aims to provide a method for efficiently recovering waste heat from drying and absorbing sulfuric acid produced from sulfur in order to solve the problems existing in the prior art. The technical principle is to set a desalted water (or condensed water) acid cooler in the air drying circulation system and the second SO3 absorption acid circulation system of sulfuric acid produced from sulfur, and use the heat from the air drying process and the second absorption process to heat all the desalted water (or condensed water) required by the high-temperature waste heat recovery system and the low-temperature waste heat recovery system in the acid-making device, and then send the heated desalted water (or condensed water) to the first SO3 circulation absorption system to send out the acid heat recovery unit, in which the desalted water (or condensed water) is first heated with 120±20℃ of external acid, and then sent out with a higher temperature. The acid string (170±25℃) heats the desalted water (or condensed water), and evaporates part of the desalted water (or condensed water) to produce 0.2±0.1MPa low-pressure steam, which is then injected into the process gas containing SO3 for primary conversion before entering the first absorption tower. The SO3 in the process gas reacts with the low-pressure steam to generate sulfuric acid, and at the same time, the low-temperature heat of the low-pressure steam is converted into heat of the process gas with a higher temperature (280±40℃). This part of heat is absorbed by the circulating acid during the absorption process in the first absorption tower, which further increases the temperature of the circulating acid. The high-temperature circulating acid generates low-pressure saturated steam (0.8±0.4MPa(g)) in the evaporator, which is equal to the amount of low-pressure steam injected.

[0019] In addition, the present invention heats the desalted water (or condensed water) with low-temperature sulfuric acid in the air drying circulation system, the second S93 absorption acid circulation system and the acid string waste heat recovery unit in sequence to produce low-pressure steam, and also heats the desalted water (or condensed water) to above the boiling point to produce deoxygenated water. In the prior art, the consumption of deoxygenated steam (0.8Pa(g)) reaches 0.15t for every ton of sulfuric acid produced. The present invention increases the output of low-pressure steam without the need to consume an additional 0.8MPa(g) of low-pressure steam, thereby achieving a substantial increase in the net output of low-pressure steam in the sulfuric acid production device.

[0020] The purpose of the present invention can be achieved by the following technical solutions

[0021] A method for efficiently recovering waste heat from drying and absorbing sulfuric acid produced from sulfur, wherein all desalted water or condensed water required by a high-temperature waste heat recovery system and a low-temperature waste heat recovery system in a sulfuric acid produced from sulfur device are sequentially heat exchanged with sulfuric acid in an air drying circulation system and a second SO3 circulation absorption system to recover process waste heat from the two circulation systems, and the desalted water or condensed water after heat exchange and temperature increase is then sent to the acid waste heat recovery unit of the first SO3 circulation absorption system to produce 0.2±0.1MPa low-pressure steam, and then the generated low-pressure steam is sprayed into the SO3-containing primary conversion process gas at the inlet of the first SO3 circulation absorption system, and the reaction heat of the low-pressure steam and SO3 chemical reaction to generate sulfuric acid is used to increase the thermal energy of the low-pressure steam to the thermal energy of a higher temperature process gas, and as the process gas after the reaction enters the first SO3 circulation absorption system, the thermal energy of this part of the 0.2±0.1MPa low-pressure steam eventually generates an equal amount of low-pressure steam in the evaporator of the first SO3 circulation absorption system.

[0022] A device for implementing the above method, the device comprises an air drying circulation system, a second SO3 circulation absorption system, and a first SO3 circulation absorption system, wherein the first SO3 circulation absorption system is provided with an acid preheating recovery unit;

[0023] The desalted water or condensed water enters the air drying acid desalted water cooler of the air drying circulation system for heat exchange, and the air drying acid desalted water cooler is located on the output pipeline at the bottom of the air drying tower;

[0024] The desalted water or condensed water from the air drying acid desalted water cooler enters the second SO3 absorption acid desalted water cooler of the second SO3 circulation absorption system for heat exchange, and the second SO3 absorption acid desalted water cooler is located on the output pipeline at the bottom of the second absorption tower;

[0025] The desalted water coming out of the second SO3 absorption acid desalted water cooler enters the acid-chain waste heat recovery unit of the first SO3 circulation absorption system for heat exchange. The acid-chain waste heat recovery unit obtains low-pressure steam, low-pressure feed water and dilution water respectively. The steam output end of the low-pressure steam is connected to the output end of the primary conversion process gas, the output end of the low-pressure feed water is connected to the evaporator, and the output end of the absorption water is connected to the mixer.

[0026] In the technical solution of the present invention, an air drying tower is provided in the air drying circulation system, an air drying acid circulation tank, an air drying circulation acid pump and an air drying acid desalted water cooler are provided in sequence on the pipeline at the output end of the bottom of the air drying tower, and part of the sulfuric acid output from the air drying acid desalted water cooler is circulated into the top of the air drying tower;

[0027] Preferably: another part of the sulfuric acid is used as the acid for the second SO3 circulation absorption system; and the air-dried acid circulation tank is also provided with an acid input terminal from the first SO3 circulation absorption system.

[0028] In the technical solution of the present invention, an air drying circulation system is provided with an air drying tower, and an air drying acid desalted water cooler, an air drying acid circulation tank and an air drying circulation acid pump are sequentially provided on the pipeline at the output end at the bottom of the air drying tower, and part of the sulfuric acid output from the air drying circulation acid pump is circulated into the top of the air drying tower;

[0029] Preferably: another part of the sulfuric acid is used as the acid for the second SO3 circulation absorption system; and the air-dried acid circulation tank is also provided with an acid input terminal from the first SO3 circulation absorption system.

[0030] In the technical solution of the present invention, a second absorption tower is provided in the second SO3 circulation absorption system, and a second absorption acid circulation tank, a second absorption acid circulation acid pump and a second SO3 absorption acid desalted water cooler are sequentially provided on the pipeline output from the bottom of the second absorption tower, and part of the sulfuric acid coming out of the second SO3 absorption acid desalted water cooler enters the top of the second absorption tower;

[0031] Preferably, another part of the sulfuric acid is output as a sulfuric acid product or as a string acid for an air drying circulation system, and the second absorption acid circulation tank is also provided with a string acid input end from the air drying circulation system.

[0032] In the technical solution of the present invention, a second absorption tower is provided in the second SO3 circulation absorption system, and a second SO3 absorption acid desalted water cooler, a second absorption acid circulation tank and a second absorption acid circulation acid pump are sequentially provided on the pipeline output from the bottom of the second absorption tower, and part of the sulfuric acid from the second absorption acid circulation acid pump enters the top of the second absorption tower;

[0033] Preferably, another part of the sulfuric acid is output as a sulfuric acid product or as a string acid for an air drying circulation system, and the second absorption acid circulation tank is also provided with a string acid input end from the air drying circulation system.

[0034] In the technical solution of the present invention, a first absorption tower is provided in the first SO3 circulation absorption system, and the bottom of the first absorption tower is connected to the first absorption acid circulation tank, the first absorption acid circulation acid pump and the evaporator in sequence, one output end of the evaporator is connected to the upper part of the first absorption tower through a mixer, and the other output end is connected to the string acid waste heat recovery unit, the low-pressure steam generated by the string acid waste heat recovery unit is connected to the output pipeline of the primary conversion process gas, the low-pressure water supply output end generated by the string acid waste heat recovery unit is connected to the evaporator, and the dilution water output end generated by the string acid waste heat recovery unit is connected to the mixer.

[0035] In the technical solution of the present invention, the acid string waste heat recovery unit includes a low-pressure feedwater heater and a low-low-pressure evaporator, the acid string output pipeline from the first SO3 circulation absorption system is connected to the low-pressure feedwater heater, the low-low-pressure evaporator and the first SO3 absorption acid desalted water cooler in sequence, and the sulfuric acid output end of the first SO3 absorption acid desalted water cooler is connected to the air drying acid circulation tank of the air drying circulation system;

[0036] The desalted water output from the second SO3 circulation absorption system passes through the first SO3 absorption acid desalted water cooler and is connected to the low-pressure evaporator in sequence. The low-pressure evaporator is provided with a low-pressure steam output end, a dilution water output end and a low-pressure feed water output end. The low-pressure feed water output end is connected to the evaporator through a low-pressure feed water pump and a low-pressure feed water heater in sequence. The dilution water output end is connected to the mixer through a jet water pump, and the low-pressure steam output end is connected to the output end of the primary conversion process gas.

[0037] In the technical solution of the present invention, the acid string waste heat recovery unit includes a low-pressure feedwater heater and a low-low-pressure evaporator, the acid string output pipeline from the first SO3 circulation absorption system is connected to the low-pressure feedwater heater, the low-low-pressure evaporator and the first SO3 absorption acid desalted water cooler in sequence, and the sulfuric acid output end of the first SO3 absorption acid desalted water cooler is connected to the air drying acid circulation tank of the air drying circulation system;

[0038] The desalted water output from the second SO3 circulation absorption system is connected to the first SO3 absorption acid desalted water cooler, one output of the first SO3 absorption acid desalted water cooler is connected to the low-low pressure evaporator, and the low-low pressure evaporator is provided with an output end of low-low pressure steam; the other output end is connected to the deaerator, the dilution water output end of the deaerator is connected to the mixer through a jet water pump, the low-pressure feed water output end of the deaerator is connected to the evaporator through a low-pressure feed water pump and a low-pressure feed water heater, and the low-low pressure steam output end of the deaerator is connected to the low-low pressure steam output end of the low-low pressure evaporator.

[0039] In the technical solution of the present invention, the acid string waste heat recovery unit includes a low-pressure feedwater heater and a low-low-pressure evaporator, the acid string output pipeline from the first SO3 circulation absorption system is connected to the low-pressure feedwater heater and the low-low-pressure evaporator respectively, the low-pressure feedwater heater and the sulfuric acid output ends of the low-low-pressure evaporator are both connected to the first SO3 absorption acid desalted water cooler, and the sulfuric acid output end of the first SO3 absorption acid desalted water cooler is connected to the air drying acid circulation tank of the air drying circulation system;

[0040] The desalted water output from the second SO3 circulation absorption system passes through the first SO3 absorption acid desalted water cooler and is connected to the low-pressure evaporator in sequence. The low-pressure evaporator is provided with a low-pressure steam output end, a dilution water output end and a low-pressure feed water output end. The low-pressure feed water output end is connected to the evaporator in sequence through a low-pressure feed water pump and a low-pressure feed water heater, and the dilution water output end is connected to the mixer through a jet water pump.

[0041] In the technical solution of the present invention, the acid string waste heat recovery unit includes a low-pressure feedwater heater and a low-low-pressure evaporator, the acid string output pipeline from the first SO3 circulation absorption system is connected to the low-pressure feedwater heater and the low-low-pressure evaporator respectively, the low-pressure feedwater heater and the sulfuric acid output ends of the low-low-pressure evaporator are both connected to the first SO3 absorption acid desalted water cooler, and the sulfuric acid output end of the first SO3 absorption acid desalted water cooler is connected to the air drying acid circulation tank of the air drying circulation system;

[0042] The desalted water output from the second SO3 circulation absorption system is connected to the first SO3 absorption acid desalted water cooler, one output of the first SO3 absorption acid desalted water cooler is connected to the low-low pressure evaporator, and the low-low pressure evaporator is provided with an output end of low-low pressure steam; the other output end is connected to the deaerator, the dilution water output end of the deaerator is connected to the mixer through a jet water pump, the low-pressure feed water output end of the deaerator is connected to the evaporator through a low-pressure feed water pump and a low-pressure feed water heater, and the low-low pressure steam output end of the deaerator is connected to the low-low pressure steam output end of the low-low pressure evaporator.

[0043] In some more specific technical solutions, the technical solutions of the present invention are as follows:

[0044] A device for drying and absorbing sulfuric acid from sulfur with high efficiency waste heat recovery, the device is composed of an air drying acid circulation system, a first SO3 circulation absorption system, and a second SO3 absorption acid circulation system. The detailed description of each system is as follows:

[0045] 1) Air drying acid circulation system

[0046] The air drying acid circulation system consists of an air drying tower, an air drying circulation pump tank, an air drying acid circulation pump, and an air drying acid desalted water cooler.

[0047] The acid side outlet of the air drying tower is connected to the air drying circulation pump tank, the acid side outlet of the air drying circulation pump tank is connected to the inlet of the air drying acid circulation pump, the outlet of the air drying acid circulation pump is connected to the acid side inlet of the air drying acid desalted water cooler, and the acid side outlet of the air drying acid desalted water cooler is further connected to the acid side inlet of the air drying tower, finally forming an air drying acid circulation loop; the acid side outlet of the air drying acid desalted water cooler also has a branch connected to the acid side inlet of the second absorption circulation tank of the second SO3 circulation absorption system, and this branch can also be connected to the finished acid delivery pipeline to send excess sulfuric acid out of the air drying acid circulation system.

[0048] The following connection method can also be adopted: the acid side outlet of the air drying tower is connected to the acid side inlet of the air drying acid desalted water cooler, the acid side outlet of the air drying acid desalted water cooler is further connected to the acid side outlet of the air drying circulation pump tank, the acid side outlet of the air drying circulation pump tank is connected to the inlet of the air drying acid circulation pump, and the air drying acid circulation pump outlet is further connected to the acid side inlet of the air drying tower, so as to form an air drying acid circulation loop; the air drying acid circulation pump outlet also has a branch connected to the acid side inlet of the second absorption circulation tank of the second S03 circulation absorption system, and this branch can also be connected to the finished acid delivery pipeline to send excess sulfuric acid out of the air drying acid circulation system.

[0049] 2) Second SO3 cycle absorption system

[0050] The second SO3 absorption acid circulation system consists of the second absorption tower, the second absorption circulation pump tank, the second absorption acid circulation pump, and the second SO3 absorption acid desalted water cooler.

[0051] The acid side outlet of the second absorption tower is connected to the second absorption circulation pump tank, the acid side outlet of the second absorption circulation pump tank is connected to the inlet of the second absorption acid circulation pump, the outlet of the second absorption acid circulation pump is connected to the acid side inlet of the second SO3 absorption acid desalted water cooler, and the acid side outlet of the second SO3 absorption acid desalted water cooler is connected to the acid side inlet of the second absorption tower, finally forming a second absorption acid circulation loop. The acid side outlet of the second SO3 absorption acid desalted water cooler also has a branch connected to the acid side inlet of the air drying circulation tank of the air drying system, and this branch can also be connected to the finished acid delivery pipeline to send excess sulfuric acid out of the second SO3 circulation absorption system.

[0052] The following connection method can also be adopted: the acid side outlet of the second absorption tower is connected to the acid side inlet of the second SO3 absorption acid desalted water cooler, the acid side outlet of the second SO3 absorption acid desalted water cooler is further connected to the acid side outlet of the second absorption circulation pump tank, the acid side outlet of the second absorption circulation pump tank is connected to the inlet of the second absorption acid circulation pump, and the second absorption acid circulation pump outlet is further connected to the acid side inlet of the second absorption tower, so as to form a second absorption acid circulation loop; the outlet of the second absorption acid circulation pump also has a branch connected to the acid side inlet of the air drying circulation tank of the air drying system, and this branch can also be connected to the finished acid delivery pipeline to send excess sulfuric acid out of the second SO3 circulation absorption system.

[0053] 3) The first SO3 cycle absorption system

[0054] The first SO3 circulation absorption system consists of: a first absorption tower, a first absorption acid circulation tank, a first absorption acid circulation acid pump, an evaporator, a mixer, and a series acid waste heat recovery unit.

[0055] The acid side outlet of the first absorption tower is connected to the first absorption circulation pump tank, the acid side outlet of the first absorption circulation pump tank is connected to the inlet of the first absorption acid circulation pump, the acid side outlet of the first absorption acid circulation pump is connected to the acid side inlet of the evaporator, the acid side outlet of the evaporator is connected to the acid side inlet of the mixer, the acid side outlet of the mixer is connected to the acid side inlet of the first absorption tower, and finally the first absorption acid circulation loop is formed. In addition, a branch is provided at the acid side outlet of the evaporator, which is connected to the acid side inlet of the acid-chain waste heat recovery unit, and the acid side outlet of the acid-chain waste heat recovery unit can be connected to the acid side inlet of the air drying circulation pump tank or the second absorption circulation pump tank, because the excess sulfuric acid in the first SO3 circulation absorption system is sent out.

[0056] The acid waste heat recovery unit can be composed of the following equipment: low-pressure feed water heater, low-pressure evaporator, first SO3 absorption acid desalted water cooler

[0057] The acid-chain waste heat recovery unit can be connected as follows: the acid-side outlet branch of the evaporator is connected to the acid-side inlet of the low-pressure feed water heater, the acid-side outlet of the low-pressure feed water heater is connected to the acid-side inlet of the low-low-pressure evaporator, the acid-side outlet of the low-low-pressure evaporator is connected to the acid-side inlet of the first SO3 absorption acid desalted water cooler, and the acid-side outlet of the first SO3 absorption acid desalted water cooler is the acid-side outlet of the acid-chain waste heat recovery unit.

[0058] The acid-chain waste heat recovery unit can be connected as follows: the acid-side outlet branch of the evaporator is connected to the acid-side inlet of the low-pressure feed water heater, and the acid-side outlet branch of the evaporator is connected to the acid-side inlet of the low-pressure evaporator, that is, the low-pressure feed water heater and the acid side of the low-pressure evaporator are in parallel, and the acid-side outlet of the low-pressure feed water heater and the acid-side outlet pipeline of the low-pressure evaporator are combined and then connected to the acid-side inlet of the first SO3 absorption acid desalted water cooler, and the acid-side outlet of the first SO3 absorption acid desalted water cooler is the acid-side outlet of the acid-chain waste heat recovery unit.

[0059] The acid waste heat recovery unit can also be composed of the following equipment: low-pressure feed water heater, low-pressure evaporator, first SO3 absorption acid desalted water cooler, deaerator

[0060] The acid-chain waste heat recovery unit can be connected as follows: the acid-side outlet branch of the evaporator is connected to the acid-side inlet of the low-pressure feed water heater, the acid-side outlet of the low-pressure feed water heater is connected to the acid-side inlet of the low-low-pressure evaporator, the acid-side outlet of the low-low-pressure evaporator is connected to the acid-side inlet of the first SO3 absorption acid desalted water cooler, and the acid-side outlet of the first SO3 absorption acid desalted water cooler is the acid-side outlet of the acid-chain waste heat recovery unit.

[0061] The acid-chain waste heat recovery unit can be connected as follows: the acid-side outlet branch of the evaporator is connected to the acid-side inlet of the low-pressure feed water heater, and the acid-side outlet branch of the evaporator is connected to the acid-side inlet of the low-pressure evaporator, that is, the low-pressure feed water heater and the acid side of the low-pressure evaporator are in parallel, and the acid-side outlet of the low-pressure feed water heater and the acid-side outlet pipeline of the low-pressure evaporator are combined and then connected to the acid-side inlet of the first SO3 absorption acid desalted water cooler, and the acid-side outlet of the first SO3 absorption acid desalted water cooler is the acid-side outlet of the acid-chain waste heat recovery unit.

[0062] A device for drying and absorbing high-efficiency waste heat recovery in sulfuric acid production from sulfur, the water side connection mode 1 is as follows:

[0063] The desalted water (or condensed water) introduced from the outside is connected to the water side inlet of the air drying acid desalted water cooler, the water side outlet of the air drying acid desalted water cooler is connected to the water side inlet of the second SO3 absorption acid desalted water cooler, the water side outlet of the second SO3 absorption acid desalted water cooler is connected to the water side inlet of the first SO3 absorption acid desalted water cooler, the water side outlet of the first SO3 absorption acid desalted water cooler is connected to the water side inlet of the low-low pressure evaporator, the low-low pressure steam outlet of the low-low pressure evaporator is connected to the primary conversion process gas pipeline of the first absorption tower; the water side outlet of the low-low pressure evaporator is respectively connected to the inlet of the low-pressure feed water pump and the inlet of the jet water pump, the outlet of the low-pressure feed water pump is connected to the water side inlet of the low-pressure feed water heater, and the outlet of the jet water pump is connected to the dilution water inlet of the mixer; the water side outlet of the low-pressure feed water heater is connected to the water side inlet of the evaporator.

[0064] A device for drying and absorbing high-efficiency waste heat recovery of sulfuric acid from sulfur, the water side of which can also be connected in the following way:

[0065] The desalted water (or condensed water) introduced from the outside is connected to the water side inlet of the air drying acid desalted water cooler, the water side outlet of the air drying acid desalted water cooler is connected to the water side inlet of the second SO3 absorption acid desalted water cooler, the water side outlet of the second SO3 absorption acid desalted water cooler is connected to the water side inlet of the first SO3 absorption acid desalted water cooler, the water side outlet of the first SO3 absorption acid desalted water cooler is respectively connected to the water side inlet of the low-pressure evaporator and the water side inlet of the deaerator, the low-pressure steam outlet of the low-pressure evaporator is connected to the primary conversion process gas pipeline of the first absorption tower; the water side outlet of the deaerator is respectively connected to the low-pressure feed water pump inlet and the jet water pump inlet, the low-pressure feed water pump outlet is connected to the water side inlet of the low-pressure feed water heater, and the jet water pump outlet is connected to the dilution water inlet of the mixer; the water side outlet of the low-pressure feed water heater is connected to the water side inlet of the evaporator.

[0066] A device for drying and absorbing high-efficiency waste heat recovery of sulfuric acid from sulfur, the water side connection mode 3 is as follows:

[0067] The desalted water (or condensed water) sent from the outside is directly connected to the water side inlet of the second SO3 absorption acid desalted water cooler, the water side outlet of the second SO3 absorption acid desalted water cooler is connected to the water side inlet of the first SO3 absorption acid desalted water cooler, the water side outlet of the first SO3 absorption acid desalted water cooler is connected to the water side inlet of the low-low pressure evaporator, the low-low pressure steam outlet of the low-low pressure evaporator is connected to the primary conversion process gas pipeline of the first absorption tower; the water side outlet of the low-low pressure evaporator is respectively connected to the inlet of the low-pressure feed water pump and the inlet of the jet water pump, the outlet of the low-pressure feed water pump is connected to the water side inlet of the low-pressure feed water heater, the outlet of the jet water pump is connected to the dilution water inlet of the mixer; the water side outlet of the low-pressure feed water heater is connected to the water side inlet of the evaporator.

[0068] A device for drying and absorbing high-efficiency waste heat recovery of sulfuric acid from sulfur, the water side of which can also be connected in the following manner:

[0069] The desalted water (or condensed water) sent from the outside is directly connected to the water side inlet of the second SO3 absorption acid desalted water cooler, the water side outlet of the second SO3 absorption acid desalted water cooler is connected to the water side inlet of the first SO3 absorption acid desalted water cooler, the water side outlet of the first SO3 absorption acid desalted water cooler is respectively connected to the water side inlet of the low-pressure evaporator and the water side inlet of the deaerator, the low-pressure steam outlet of the low-pressure evaporator is connected to the primary conversion process gas pipeline of the first absorption tower; the water side outlet of the deaerator is respectively connected to the low-pressure feed water pump inlet and the jet water pump inlet, the low-pressure feed water pump outlet is connected to the water side inlet of the low-pressure feed water heater, the jet water pump outlet is connected to the dilution water inlet of the mixer; the water side outlet of the low-pressure feed water heater is connected to the water side inlet of the evaporator.

[0070] A method for efficiently recovering waste heat from a drying and absorption process for sulfuric acid production from sulfur: the method comprises the following steps:

[0071] 1) The room temperature desalted water (or condensed water) sent from the outside enters the air drying acid desalted water cooler, recovers the heat in the air drying acid circulation process, and heats the desalted water (or condensed water) to 40±10℃.

[0072] 2) The desalted water (or condensed water) at the outlet of the air-dried acid desalted water cooler is then sent to the second SO3 absorption acid desalted water cooler to recover the heat in the second absorption cycle process and heat the desalted water (or condensed water) to 65±10°C.

[0073] 3) The desalted water (or condensed water) at the outlet of the second SO3 absorption acid desalted water cooler is then sent to the first SO3 absorption acid desalted water cooler to recover the heat of 120±20℃ of the high-temperature acid sent out of the first absorption cycle, and the temperature of the desalted water (or condensed water) is heated to 85±10℃. The high-temperature acid (170±25℃) is then used to generate 0.2±0.1MPa low-pressure steam in the low-pressure evaporator or low-pressure evaporator, and then these low-pressure steams are sprayed into the primary conversion process gas entering the first absorption tower. The SO3 in the process gas reacts with the low-pressure steam to generate sulfuric acid, and at the same time, the low-temperature heat of the low-pressure steam is converted into the heat of the higher temperature process gas (280±40℃). This part of the heat is absorbed by the circulating acid in the first absorption tower along with the absorption reaction, so that the temperature of the circulating acid is further increased, and the high-temperature circulating acid generates an equal amount of (0.8±0.4MPa(g)) of low-pressure saturated steam in the evaporator of the first SO3 circulation absorption system.

[0074] When the desalted water (or condensed water) sent from the outside of the boundary area has been heated by the heater in other process, step 1 can be omitted, and the desalted water (or condensed water) can be directly sent to the second absorption deionized acid cooler. The subsequent steps remain unchanged, and the purpose of increasing the steam production of the evaporator of the first SO3 circulation absorption system can also be achieved. At this time, the drying circulation system can use the circulating water cooling process.

[0075] In the technical solution of the present invention: an air drying acid desalted water cooler is arranged in the air drying acid circulation system for sulfuric acid production from sulfur, the acid side inlet of the acid cooler can be connected to the outlet of the air drying circulation acid pump, and the acid side outlet is connected to the acid side inlet of the air drying tower; the acid side inlet of the acid cooler can also be connected to the acid side outlet of the air drying tower, and the acid side outlet of the acid cooler is connected to the inlet of the air drying acid circulation tank;

[0076] In the technical solution of the present invention: a second SO3 absorption acid desalted water cooler is arranged in the second SO3 absorption acid circulation system of sulfuric acid production from sulfur, the acid side inlet of the acid cooler can be connected to the outlet of the second absorption circulation acid pump, and the acid side outlet is connected to the acid side inlet of the second absorption tower; the acid side inlet of the acid cooler can also be connected to the acid side outlet of the second absorption tower, and the acid side outlet of the acid cooler is connected to the inlet of the acid circulation tank of the second absorption tower;

[0077] In the technical solution of the present invention: a first SO3 absorption acid desalted water cooler is arranged in the acid waste heat recovery unit of the first SO3 circulation absorption system for sulfuric acid production from sulfur, the acid side inlet of the acid cooler is connected to the acid side outlet of the upstream waste heat recovery equipment, and the acid side outlet is connected to an external acid delivery pipeline, and the external acid delivery pipeline sends the cooled acid to an air drying circulation system and a second SO3 absorption acid circulation system.

[0078] In the technical solution of the present invention: the water side of the air-dried acid desalted water cooler can be connected in series with the second SO3 absorption acid desalted water cooler, and then connected in series with the first SO3 absorption acid desalted water cooler. The desalted water (or condensed water) is heated by the above-mentioned acid coolers in turn to recover the waste heat of the process.

[0079] In the technical solution of the present invention, only the second SO3 absorption acid desalted water cooler can be connected in series with the first SO3 absorption acid desalted water cooler. The desalted water (or condensed water) is heated by the above acid cooler in turn to recover the waste heat of the process.

[0080] In the technical solution of the present invention: in the acid waste heat recovery unit of the first SO3 circulation absorption system, the low-pressure evaporator and the acid side of the first SO3 absorption acid desalted water cooler can be connected in series, and the external sulfuric acid is cooled and recovered through the low-pressure evaporator and the first SO3 absorption acid desalted water cooler in turn to recover heat, and the desalted water (or condensed water) is heated to produce deoxygenated water and 0.2±0.1MPa low-pressure steam.

[0081] In the technical solution of the present invention: two devices, a low-pressure evaporator and a deaerator, can also be set in the acid waste heat recovery unit of the first SO3 circulation absorption system. The low-pressure evaporator and the acid side of the first SO3 absorption acid desalted water cooler are connected in series. The external sulfuric acid is cooled and cooled in turn through the low-pressure evaporator and the first SO3 absorption acid desalted water cooler to recover heat. A part of the desalted water (or condensed water) is sent to the low-pressure evaporator to generate 0.2±0.1MPa low-pressure steam, and the other part is reduced in pressure in the deaerator to produce deoxygenated water without the need to consume additional low-pressure steam.

[0082] In the technical solution of the present invention: the low-pressure steam outlet of the low-pressure evaporator is connected to the primary conversion process gas pipe containing SO3 sent to the first absorption tower, and the output 0.2±0.1MPa is sprayed into the primary conversion process gas.

[0083] Beneficial effects of the present invention:

[0084] The device and method for efficiently recovering waste heat from the drying and absorption process of sulfuric acid produced from sulfur are adopted to recover waste heat from the drying and absorption process of sulfuric acid produced from sulfur, generate more 0.2±0.1MPa low-pressure steam, and then spray the generated low-pressure steam into the primary conversion process gas containing SO3 entering the inlet of the first absorption tower, and the evaporator of the first SO3 circulation absorption system generates an equal amount of (0.8±0.4MPa(g)) low-pressure saturated steam, thereby achieving a waste heat recovery rate of more than 95% from the drying and absorption process of sulfuric acid produced from sulfur. At the same time, the deaerator of the waste heat recovery system does not need to consume low-pressure steam, so that the net steam production rate per ton of acid reaches 0.6 tons of low-pressure steam per ton of acid, which is a significant improvement over the net steam production rate of 0.3 tons of low-pressure steam per ton of acid in the prior art. BRIEF DESCRIPTION OF THE DRAWINGS

[0085] Figure 1 This is a schematic diagram of Example 1 of the present invention.

[0086] Figure 2 A schematic diagram of an air drying cycle system.

[0087] Figure 3 A schematic diagram of another air drying cycle system.

[0088] Figure 4 Schematic diagram of a second SO3 cycle absorption system.

[0089] Figure 5 Schematic diagram of another second SO3 cycle absorption system.

[0090] Figure 6 Schematic diagram of the first SO3 cycle absorption system.

[0091] Figure 7 This is a schematic diagram of the first type of acid waste heat recovery unit.

[0092] Figure 8 This is a schematic diagram of the second type of acid waste heat recovery unit.

[0093] Fig. 9 This is a schematic diagram of the third type of acid waste heat recovery unit.

[0094] Fig.10 This is a schematic diagram of the fourth type of acid waste heat recovery unit.

[0095] Fig.11 This is a schematic diagram of waste heat recovery in Example 6.

[0096] Among them, 11-air drying tower, 12-air drying acid circulation tank, 13-air drying circulating acid pump, 14-air drying acid desalted water cooler;

[0097] 21-first absorption tower, 22-first absorption acid circulation tank, 23-first absorption acid circulation acid pump, 24-evaporator, 25-mixer;

[0098] 31-second absorption tower, 32-second absorption acid circulation tank, 33-second absorption acid circulation acid pump, 34-second SO3 absorption acid desalted water cooler;

[0099] 41- low pressure feed water heater, 42- low pressure evaporator, 43- deaerator, 44- first SO3 absorption acid desalted water cooler, 45- low pressure feed water pump, 46- jet water pump. DETAILED DESCRIPTION

[0100] The present invention will be further described below in conjunction with embodiments, but the protection scope of the present invention is not limited thereto:

[0101] like Figure 1 The device comprises an air drying circulation system, a second SO3 circulation absorption system, and a first SO3 circulation absorption system, wherein the first SO3 circulation absorption system is provided with an acid preheating recovery unit;

[0102] Desalted water or condensed water enters the air drying acid desalted water cooler 14 of the air drying circulation system for heat exchange, and the air drying acid desalted water cooler 14 is located on the output pipeline at the bottom of the air drying tower;

[0103] The desalted water or condensed water from the air-dried acid desalted water cooler 14 enters the second SO3 absorption acid desalted water cooler 34 of the second SO3 circulation absorption system for heat exchange, and the second SO3 absorption acid desalted water cooler 34 is located on the output pipeline at the bottom of the second absorption tower;

[0104] The desalted water coming out of the second SO3 absorption acid desalted water cooler 34 enters the acid-chain waste heat recovery unit of the first SO3 circulation absorption system for heat exchange. The acid-chain waste heat recovery unit obtains low-pressure steam, low-pressure feed water and dilution water respectively. The steam output end of the low-pressure steam is connected to the output end of the primary conversion process gas, the output end of the low-pressure feed water is connected to the evaporator, and the output end of the absorption water is connected to the mixer.

[0105] like Figure 2The air drying circulation system is provided with an air drying tower, and the pipeline at the output end of the bottom of the air drying tower is provided with an air drying acid circulation tank 12, an air drying circulation acid pump 13 and an air drying acid desalted water cooler 14 in sequence, and part of the sulfuric acid output from the air drying acid desalted water cooler 14 is circulated into the top of the air drying tower 11;

[0106] Another part of the sulfuric acid is used as the acid for the second SO3 circulation absorption system; the air-dried acid circulation tank 12 is also provided with an acid input terminal from the first SO3 circulation absorption system.

[0107] like Figure 3 The air drying circulation system is provided with an air drying tower, and the pipeline at the output end of the bottom of the air drying tower is provided with an air drying acid desalted water cooler 14, an air drying acid circulation tank 12 and an air drying circulation acid pump 13 in sequence, and part of the sulfuric acid output from the air drying circulation acid pump 13 is circulated into the top of the air drying tower 11;

[0108] Another part of the sulfuric acid is used as the acid for the second SO3 circulation absorption system; the air-dried acid circulation tank 12 is also provided with an acid input terminal from the first SO3 circulation absorption system.

[0109] like Figure 4 The second SO3 circulation absorption system is provided with a second absorption tower 31, and the second absorption acid circulation tank 32, the second absorption acid circulation acid pump 33 and the second SO3 absorption acid desalted water cooler 34 are sequentially provided on the pipeline output from the bottom of the second absorption tower 31, and part of the sulfuric acid coming out of the second SO3 absorption acid desalted water cooler enters the top of the second absorption tower;

[0110] Another part of the sulfuric acid is output as a sulfuric acid product or as a string acid for the air drying circulation system. The second absorption acid circulation tank 32 is also provided with a string acid input end from the air drying circulation system.

[0111] like Figure 5 The second SO3 circulation absorption system is provided with a second absorption tower 31, and the pipeline output from the bottom of the second absorption tower 31 is provided with a second SO3 absorption acid desalted water cooler 34, a second absorption acid circulation tank 32 and a second absorption acid circulation acid pump 33 in sequence, and part of the sulfuric acid coming out of the second absorption acid circulation acid pump 33 enters the top of the second absorption tower;

[0112] Another part of the sulfuric acid is output as a sulfuric acid product or as a string acid for the air drying circulation system. The second absorption acid circulation tank 32 is also provided with a string acid input end from the air drying circulation system.

[0113] like Figure 6A first absorption tower 21 is provided in the first SO3 circulation absorption system, and the bottom of the first absorption tower 21 is connected to the first absorption acid circulation tank 22, the first absorption acid circulation acid pump 23 and the evaporator 24 in sequence. One output end of the evaporator 24 is connected to the upper part of the first absorption tower 21 through a mixer 25, and the other output end is connected to the string acid waste heat recovery unit. The low-pressure steam generated by the string acid waste heat recovery unit is connected to the output pipeline of the primary conversion process gas, the low-pressure feed water output end generated by the string acid waste heat recovery unit is connected to the evaporator 24, and the dilution water output end generated by the string acid waste heat recovery unit is connected to the mixer 25.

[0114] like Figure 7 The string acid waste heat recovery unit includes a low-pressure feed water heater 41 and a low-low pressure evaporator 42. The string acid output pipeline from the first SO3 circulation absorption system is connected to the low-pressure feed water heater 41, the low-low pressure evaporator 42 and the first SO3 absorption acid desalted water cooler 44 in sequence. The sulfuric acid output end of the first SO3 absorption acid desalted water cooler 44 is connected to the air drying acid circulation tank 12 of the air drying circulation system.

[0115] The desalted water output from the second SO3 circulation absorption system passes through the first SO3 absorption acid desalted water cooler 44 and is connected to the low-pressure evaporator 42 in sequence. The low-pressure evaporator 42 is provided with a low-pressure steam output end, a dilution water output end and a low-pressure feed water output end. The low-pressure feed water output end is connected to the evaporator 24 in sequence through a low-pressure feed water pump 45 and a low-pressure feed water heater 41. The dilution water output end is connected to the mixer 25 through a jet water pump 46. The low-pressure steam output end is connected to the output end of the primary conversion process gas.

[0116] like Figure 8 The string acid waste heat recovery unit includes a low-pressure feed water heater 41 and a low-low pressure evaporator 42. The string acid output pipeline from the first SO3 circulation absorption system is connected to the low-pressure feed water heater 41, the low-low pressure evaporator 42 and the first SO3 absorption acid desalted water cooler 44 in sequence. The sulfuric acid output end of the first SO3 absorption acid desalted water cooler 44 is connected to the air drying acid circulation tank 12 of the air drying circulation system.

[0117] The desalted water output from the second SO3 circulation absorption system is connected to the first SO3 absorption acid desalted water cooler 44, one output of the first SO3 absorption acid desalted water cooler 44 is connected to the low-pressure evaporator 42, and the low-pressure evaporator 42 is provided with an output end for low-pressure steam; the other output end is connected to the deaerator 43, the dilution water output end of the deaerator 43 is connected to the mixer 25 through the jet water pump 46, the low-pressure feed water output end of the deaerator 43 is connected to the evaporator 24 through the low-pressure feed water pump 45 and the low-pressure feed water heater 41, and the low-pressure steam output end of the deaerator 43 is connected to the low-pressure steam output end of the low-pressure evaporator 42.

[0118] like Fig. 9 The string acid waste heat recovery unit includes a low-pressure feed water heater 41 and a low-pressure evaporator 42. The string acid output pipeline from the first SO3 circulation absorption system is connected to the low-pressure feed water heater 41 and the low-pressure evaporator 42 respectively. The sulfuric acid output ends of the low-pressure feed water heater 41 and the low-pressure evaporator 42 are both connected to the first SO3 absorption acid desalted water cooler 44. The sulfuric acid output end of the first SO3 absorption acid desalted water cooler 44 is connected to the air drying acid circulation tank 12 of the air drying circulation system;

[0119] The desalted water output from the second SO3 circulation absorption system passes through the first SO3 absorption acid desalted water cooler 44 and is connected to the low-pressure evaporator 42 in sequence. The low-pressure evaporator 42 is provided with a low-pressure steam output end, a dilution water output end and a low-pressure feed water output end. The low-pressure feed water output end is connected to the evaporator 24 in sequence through a low-pressure feed water pump 45 and a low-pressure feed water heater 41, and the dilution water output end is connected to the mixer 25 through a jet water pump 46.

[0120] like Fig.10 The string acid waste heat recovery unit includes a low-pressure feed water heater 41 and a low-pressure evaporator 42. The string acid output pipeline from the first SO3 circulation absorption system is connected to the low-pressure feed water heater 41 and the low-pressure evaporator 42 respectively. The sulfuric acid output ends of the low-pressure feed water heater 41 and the low-pressure evaporator 42 are both connected to the first SO3 absorption acid desalted water cooler 44. The sulfuric acid output end of the first SO3 absorption acid desalted water cooler 44 is connected to the air drying acid circulation tank 12 of the air drying circulation system;

[0121] The desalted water output from the second SO3 circulation absorption system is connected to the first SO3 absorption acid desalted water cooler 44, one output of the first SO3 absorption acid desalted water cooler 44 is connected to the low-pressure evaporator 42, and the low-pressure evaporator 42 is provided with an output end for low-pressure steam; the other output end is connected to the deaerator 43, the dilution water output end of the deaerator 43 is connected to the mixer 25 through the jet water pump 46, the low-pressure feed water output end of the deaerator 43 is connected to the evaporator 24 through the low-pressure feed water pump 45 and the low-pressure feed water heater 41, and the low-pressure steam output end of the deaerator 43 is connected to the low-pressure steam output end of the low-pressure evaporator 42.

[0122] Example 1

[0123] Step 1 Figure 2

[0124] Sulfuric acid (concentration 97.5%, temperature 55°C) at the outlet of the air drying tower 11 enters the air drying acid circulation tank 12 and is mixed with the externally sent string acid (concentration 99.4%, temperature 90°C) of the first SO3 circulation absorption system, and the concentration is increased to 98%, and the temperature is raised to 65°C. The sulfuric acid is pressurized by the air drying circulation acid pump 13 and sent to the air drying acid desalted water cooler 14, and the 20°C desalted water (or condensed water) sent outside the boundary area is heated to 50°C, and then sent to the inlet of the second SO3 absorption acid desalted water cooler 34. After cooling, the circulating acid returns to the acid inlet of the air drying tower 11, and the excess sulfuric acid in the air drying circulation system is sent to the second absorption acid circulation tank 32 of the second SO3 circulation absorption system through the acid side outlet branch of the air drying acid desalted water cooler 14, or sent to the finished acid delivery pipeline.

[0125] See step 2 Figure 4

[0126] The acid concentration at the outlet of the second absorption tower 31 is 98.8% and the temperature is 80°C. After sulfuric acid enters the second absorption acid circulation tank 32 and mixes with the lower concentration acid (98%) and process water sent from the air drying circulation system, the concentration is reduced to 98.5% and the temperature is raised to 85°C. The sulfuric acid is pressurized by the second absorption circulation acid pump 33 and sent to the second SO3 absorption acid desalted water cooler 34. The water heated at 50°C by the air drying acid desalted water cooler 14 is heated to 75°C, and the circulating acid is returned to the acid inlet of the second absorption tower 31 after cooling. The SO3 in the secondary conversion process gas is circulated and absorbed. The excess sulfuric acid in the second SO3 circulation absorption system is sent to the air drying acid circulation tank 12 of the air drying circulation system through the acid side outlet branch of the second SO3 absorption acid desalted water cooler 34, or sent to the finished acid delivery pipeline.

[0127] See step 3 Figure 6 , Figure 7

[0128] The desalted water (or condensed water) with a water outlet temperature of 75°C from the second SO3 absorption acid desalted water cooler 34 enters the acid waste heat recovery unit. The desalted water (or condensed water) is heated to 95°C by 140°C sulfuric acid and then sent to the low-pressure evaporator 42, where it is heated by 180°C sulfuric acid. In the low-pressure evaporator 42, the desalted water (or condensed water) is heated by sulfuric acid to produce 0.1MPa low-pressure steam. For every ton of sulfuric acid produced, 0.1t of low-pressure steam can be produced. 2. The desalted water (or condensed water) is partially evaporated, and the dissolved oxygen is taken out by the low-pressure steam. The remaining water is deoxygenated water, which is sent out by the low-pressure feed water pump 45 and the jet water pump 46. A part of the deoxygenated water is pressurized by the low-pressure feed water pump 45 to be low-pressure feed water and sent to the low-pressure feed water heater 41, and is heated by the 190°C sulfuric acid at the outlet branch of the evaporator 24. After the water temperature rises to 175°C, it is sent to the evaporator 24; the other part of the deoxygenated water is pressurized by the jet water pump 46 and sent to the mixer 25 as dilution water to adjust the concentration of sulfuric acid entering the first absorption tower 21. The low-pressure steam generated by the low-pressure evaporator 42 is sprayed into the primary conversion process gas entering the inlet of the first absorption tower 21. The SO3 in the process gas reacts with the low-pressure steam to generate sulfuric acid. At the same time, the low-temperature heat of the low-pressure steam is also converted into the heat of the higher-temperature process gas. The process gas temperature rises to 300°C and then enters the first absorption tower 21. The heat of the high-temperature process gas is absorbed by the acid sprayed in the upper part. After leaving the first absorption tower, the temperature of the sulfuric acid rises to 215°C and enters the first absorption acid circulation tank 22. It is then pressurized and sent to the evaporator 24 by the first absorption acid circulation acid pump 23. In the evaporator 24, the low-pressure feed water exchanges heat with the high-temperature concentrated sulfuric acid at 215°C to evaporate and generate 0.8MPa(g) of low-pressure saturated steam. For every ton of sulfuric acid produced, 0.6t of low-pressure saturated steam can be generated.

[0129] The first SO3 circulation absorption system acid side process is as follows: 99% sulfuric acid is sprayed into the upper part of the first absorption tower 21 to react with the 300°C process gas sent from the lower part of the tower to generate high-temperature and high-concentration sulfuric acid (temperature 215°C, concentration 99.4%) at the bottom of the tower. The high-temperature and high-concentration sulfuric acid enters the first absorption acid circulation tank 22. It is then pressurized and sent to the evaporator 24 by the first absorption acid circulation acid pump 23, and heat exchanged with the low-pressure feed water to produce 0.8MPa(g) low-pressure saturated steam. The acid temperature is reduced to 190°C, and then most of the sulfuric acid is sent to the mixer 25. The outlet dilution water of the jet water pump 46 is used to adjust the concentration to 99%. The sulfuric acid temperature is raised to 195°C. The sulfuric acid from the mixer 25 enters the first absorption acid circulation tank 22. The upper part of the absorption tower 21 circulates and reacts with the process gas; another part of the sulfuric acid (temperature 190°C, concentration 99.4%) at the outlet of the evaporator 24 enters the low-pressure feed water heater 41 of the acid waste heat recovery unit, and is sent to the low-pressure feed water by the low-pressure feed water pump 45 for heat exchange. The acid temperature is reduced to 180°C, and then sent to the low-low pressure evaporator 42 to heat the desalted water (or condensed water) to produce low-low pressure steam, and the acid temperature is reduced to 140°C. The sulfuric acid exits the low-low pressure evaporator 42 and enters the first SO3 absorption acid desalted water cooler 44 to exchange heat with the desalted water (or condensed water). The acid temperature is reduced to 90°C and is sent to the air drying acid circulation tank 12 of the air drying circulation system to adjust the acid concentration of the air drying circulation system.

[0130] Example 2

[0131] Step 1 Figure 3

[0132] The sulfuric acid (concentration 97.5%, temperature 65°C) at the outlet of the air drying tower 11 enters the air drying acid desalted water cooler 14, and is cooled by desalted water (or condensed water) sent from outside the boundary area to 50°C. After that, it enters the air drying acid circulation tank 12 and mixes with the external string acid (concentration 99.4%, temperature 90°C) of the first SO3 circulation absorption system. The temperature and concentration are increased, and then the sulfuric acid is pressurized by the air drying circulation acid pump 13 and sent to the sulfuric acid inlet of the air drying tower 11 to circulate and absorb moisture in the air; the excess sulfuric acid in the air drying circulation system is sent to the second absorption acid circulation tank 32 of the second SO3 circulation absorption system through the outlet branch of the air drying circulation acid pump 13, or is sent to the finished acid delivery pipeline.

[0133] 20°C desalted water (or condensed water) is sent from outside the boundary area, heated to 50°C by the air-dried acid desalted water cooler 14, and then sent to the water side inlet of the second SO3 absorption acid desalted water cooler 34.

[0134] See step 2 Figure 5

[0135] The acid concentration at the outlet of the second absorption tower 31 is 98.8%, and the temperature is 85°C. The sulfuric acid enters the second SO3 absorption acid desalted water cooler 34. After being cooled to 70°C by the equipment, the sulfuric acid is sent to the second absorption circulation pump tank 32. After mixing with the lower concentration acid (98%) and process water sent by the air drying circulation system, the concentration is reduced to 98.5%, and the temperature is raised to 75°C. The sulfuric acid is pressurized by the second absorption circulation acid pump 33 and sent to the second absorption tower 31 sulfuric acid inlet circulation absorption circulation to absorb the SO3 in the secondary conversion process gas. The excess sulfuric acid in the second SO3 circulation absorption system is sent to the air drying acid circulation tank 12 of the air drying circulation system through the outlet branch of the second absorption acid circulation pump 33, or sent to the finished acid delivery pipeline.

[0136] The 50°C desalted water (or condensed water) sent from the water side outlet of the air-dried acid desalted water cooler 14 is heated to 75°C by the second SO3 absorption acid desalted water cooler 34 and then sent to the first SO3 absorption acid desalted water cooler 44 of the acid chain waste heat recovery unit.

[0137] See step 3 Figure 6 , Figure 7

[0138] This step is the same as step 3 of Example 1.

[0139] Example 3

[0140] Step 1

[0141] Step 1

[0142] Step 2

[0143] Adopt Implementation Benefits 1 Step 2

[0144] See step 3 Figure 6 , Figure 8

[0145] The desalted water (or condensed water) with a water side outlet temperature of 75°C from the second SO3 absorption acid desalted water cooler 34 enters the acid chain waste heat recovery unit. The desalted water (or condensed water) is heated to 95°C with 140°C sulfuric acid, and then part of the heated desalted water (or condensed water) is sent to the low-pressure evaporator 42 and heated with 180°C sulfuric acid. In the low-pressure evaporator 42, the desalted water (or condensed water) is heated by sulfuric acid to produce 0.1MPa low-pressure steam. For every ton of sulfuric acid produced, 0.1t of low-pressure steam can be produced. Another part of the desalted water (or condensed water) from the first SO3 absorption acid desalted water cooler is used to cool the desalted water. The condensed water) is sent to the deaerator 43, the working pressure of which is 0.05MPa. After heating, the desalted water (or condensed water) is depressurized and evaporated in the equipment for thermal deoxygenation. No external steam is required to produce deoxygenated water. The deoxygenated water is sent out through the low-pressure feed water pump 45 and the jet water pump 46. A part of the deoxygenated water is pressurized by the low-pressure feed water pump 45 into the low-pressure feed water and sent to the low-pressure feed water heater 41, heated by the 190°C sulfuric acid at the outlet branch of the evaporator 24, and sent to the evaporator 24 after the water temperature is raised to 175°C; the other part of the deoxygenated water is pressurized by the jet water pump 46 and sent to the mixer 25 as dilution water to adjust the concentration of sulfuric acid entering the first absorption tower 21. The low-pressure steam generated by the low-pressure evaporator 42 is sprayed into the primary conversion process gas entering the first absorption tower 21. The SO3 in the process gas reacts with the low-pressure steam to generate sulfuric acid. At the same time, the low-temperature heat of the low-pressure steam is also converted into the heat of the higher-temperature process gas. The process gas temperature rises to 300°C and then enters the first absorption tower 21. The heat of the high-temperature process gas is absorbed by the acid sprayed in the upper part. After leaving the first absorption tower, the temperature of the sulfuric acid rises to 215°C and enters the first absorption acid circulation tank 22. It is then pressurized and sent to the evaporator 24 by the first absorption acid circulation acid pump 23. In the evaporator 24, the low-pressure feed water exchanges heat with the high-temperature concentrated sulfuric acid at 215°C to evaporate and generate 0.8MPa(g) of low-pressure saturated steam. For every ton of sulfuric acid produced, 0.6t of low-pressure saturated steam can be generated.

[0146] The first SO3 circulation absorption system acid side process is as follows: 99% sulfuric acid is sprayed into the upper part of the first absorption tower 21 to react with the 300°C process gas sent from the lower part of the tower to generate high-temperature and high-concentration sulfuric acid (temperature 215°C, concentration 99.4%) at the bottom of the tower. The high-temperature and high-concentration sulfuric acid enters the first absorption acid circulation tank 22. It is then pressurized and sent to the evaporator 24 by the first absorption acid circulation acid pump 23, and heat exchanged with the low-pressure feed water to produce 0.8MPa(g) low-pressure saturated steam. The acid temperature is reduced to 190°C, and then most of the sulfuric acid is sent to the mixer 25. The outlet dilution water of the jet water pump 46 is used to adjust the concentration to 99%. The sulfuric acid temperature is raised to 195°C. The sulfuric acid from the mixer 25 enters the first absorption acid circulation tank 22. The upper part of the absorption tower 21 circulates and reacts with the process gas; another part of the sulfuric acid (temperature 190°C, concentration 99.4%) at the outlet of the evaporator 24 enters the low-pressure feed water heater 41 of the acid waste heat recovery unit, and is sent to the low-pressure feed water by the low-pressure feed water pump 45 for heat exchange. The acid temperature is reduced to 180°C, and then sent to the low-low pressure evaporator 42 to heat the desalted water (or condensed water) to produce low-low pressure steam, and the acid temperature is reduced to 140°C. The sulfuric acid exits the low-low pressure evaporator 42 and enters the first SO3 absorption acid desalted water cooler 44 to exchange heat with the desalted water (or condensed water). The acid temperature is reduced to 90°C and is sent to the air drying acid circulation tank 12 of the air drying circulation system to adjust the acid concentration of the air drying circulation system.

[0147] Example 4

[0148] Step 1

[0149] Step 1

[0150] Step 2

[0151] Adopt Implementation Benefits 1 Step 2

[0152] See step 3 Figure 6 , Fig. 9

[0153] The desalted water (or condensed water) with a water outlet temperature of 75°C from the second SO3 absorption acid desalted water cooler 34 enters the acid waste heat recovery unit for the first SO3 absorption acid desalted water cooler 44, where the water temperature is raised to 95°C by heating with 140°C sulfuric acid, and then sent to the low-pressure evaporator 42, where it is heated with a portion of 190°C sulfuric acid from the outlet branch of the evaporator 24. In the low-pressure evaporator 42, the desalted water (or condensed water) is heated by sulfuric acid to produce 0.1MPa low-pressure steam. For every ton of sulfuric acid produced, 0.1t of low-pressure steam can be produced. The desalted water (or condensed water) in the evaporator 42 is partially evaporated, and the dissolved oxygen is carried out by the low-pressure steam. The remaining water is deoxygenated water, which is sent out by the low-pressure feed water pump 45 and the jet water pump 46. A part of the deoxygenated water is pressurized by the low-pressure feed water pump 45 to be low-pressure feed water and sent to the low-pressure feed water heater 41, and is heated with another part of 190°C sulfuric acid at the outlet branch of the evaporator 24. After the water temperature is raised to 175°C, it is sent to the evaporator 24; another part of the deoxygenated water is pressurized by the jet water pump 46 and sent to the mixer 25 as dilution water to adjust the concentration of sulfuric acid entering the first absorption tower 21. The low-pressure steam generated by the low-pressure evaporator 42 is sprayed into the primary conversion process gas entering the first absorption tower 21. The SO3 in the process gas reacts with the low-pressure steam to generate sulfuric acid. At the same time, the low-temperature heat of the low-pressure steam is also converted into the heat of the higher-temperature process gas. The process gas temperature rises to 300°C and then enters the first absorption tower 21. The heat of the high-temperature process gas is absorbed by the acid sprayed in the upper part. After leaving the first absorption tower, the temperature of the sulfuric acid rises to 215°C and enters the first absorption acid circulation tank 22. It is then pressurized and sent to the evaporator 24 by the first absorption acid circulation acid pump 23. In the evaporator 24, the low-pressure feed water exchanges heat with the high-temperature concentrated sulfuric acid at 215°C to evaporate and generate 0.8MPa(g) of low-pressure saturated steam. For every ton of sulfuric acid produced, 0.6t of low-pressure saturated steam can be generated.

[0154] The first SO3 circulation absorption system acid side process is as follows: 99% sulfuric acid is sprayed into the upper part of the first absorption tower 21 to react with the 300°C process gas sent from the lower part of the tower, and high-temperature and high-concentration sulfuric acid (temperature 215°C, concentration 99.4%) is generated at the bottom of the tower. The high-temperature and high-concentration sulfuric acid enters the first absorption acid circulation tank 22. It is then pressurized and sent to the evaporator 24 by the first absorption acid circulation acid pump 23, and heat exchanged with the low-pressure feed water to produce 0.8MPa(g) low-pressure saturated steam. The acid temperature is reduced to 190°C, and then most of the sulfuric acid is sent to the mixer 25. The concentration is adjusted to 99% by the dilution water at the outlet of the jet water pump 46. The sulfuric acid temperature is raised to 195°C. The sulfuric acid discharged from the mixer 25 enters the upper part of the first absorption tower 21 to circulate and react with the process gas; another part of the sulfuric acid (temperature 190 ℃, concentration 99.4%) respectively enter the low-pressure feed water heater 41 and the low-pressure evaporator 42 of the acid series waste heat recovery unit, a part of the sulfuric acid (temperature 190 ℃, concentration 99.4%) is sent to the low-pressure feed water for heat exchange with the low-pressure feed water pump 45, and the acid temperature is reduced to 140 ℃, and the other part of the sulfuric acid (temperature 190 ℃, concentration 99.4%) enters the low-pressure evaporator 42, heats the desalted water (or condensed water) to generate low-pressure steam, and the acid temperature is reduced to 140 ℃; the sulfuric acid at the outlets of the low-pressure feed water heater 41 and the low-pressure evaporator 42 is combined and enters the first SO3 absorption acid desalted water cooler 44 to exchange heat with the desalted water (or condensed water) to reduce the acid temperature to 90 ℃ and is sent to the air drying acid circulation tank 12 of the air drying circulation system to adjust the acid concentration of the air drying circulation system.

[0155] Example 5

[0156] Step 1

[0157] Step 1

[0158] Step 2

[0159] Adopt Implementation Benefits 1 Step 2

[0160] See step 3 Figure 6 , Fig.10

[0161] The desalted water (or condensed water) with a water side outlet temperature of 75°C from the second SO3 absorption acid desalted water cooler 34 enters the acid chain waste heat recovery unit. The desalted water (or condensed water) is heated to 95°C with 140°C sulfuric acid, and then part of the heated desalted water (or condensed water) is sent to the low-pressure evaporator 42, and then heated with a part of the 190°C sulfuric acid from the outlet branch of the evaporator 24. In the low-pressure evaporator 42, the desalted water (or condensed water) is heated by sulfuric acid to produce 0.1MPa low-pressure steam. For every ton of sulfuric acid produced, 0.1t of low-pressure steam can be produced. Another part of the desalted water (or condensed water) from the first SO3 absorption acid desalted water cooler is used to heat the water. Water (or condensed water) is sent to the deaerator 43, the working pressure of which is 0.05 MPa. After heating, the desalted water (or condensed water) is depressurized and evaporated in the equipment for thermal deoxygenation, and no external steam is required to produce deoxygenated water. The deoxygenated water is sent out through the low-pressure feed water pump 45 and the jet water pump 46. A part of the deoxygenated water is pressurized by the low-pressure feed water pump 45 into low-pressure feed water and sent to the low-pressure feed water heater 41, and heated with another part of 190°C sulfuric acid at the outlet branch of the evaporator 24. After the water temperature is raised to 175°C, it is sent to the evaporator 24; another part of the deoxygenated water is pressurized by the jet water pump 46 and sent to the mixer 25 as dilution water to adjust the concentration of sulfuric acid entering the first absorption tower 21. The low-pressure steam generated by the low-pressure evaporator 42 is sprayed into the primary conversion process gas entering the first absorption tower 21. The SO3 in the process gas reacts with the low-pressure steam to generate sulfuric acid. At the same time, the low-temperature heat of the low-pressure steam is also converted into the heat of the higher-temperature process gas. The process gas temperature rises to 300°C and then enters the first absorption tower 21. The heat of the high-temperature process gas is absorbed by the acid sprayed in the upper part. After leaving the first absorption tower, the temperature of the sulfuric acid rises to 215°C and enters the first absorption acid circulation tank 22. It is then pressurized and sent to the evaporator 24 by the first absorption acid circulation acid pump 23. In the evaporator 24, the low-pressure feed water exchanges heat with the high-temperature concentrated sulfuric acid at 215°C to evaporate and generate 0.8MPa(g) of low-pressure saturated steam. For every ton of sulfuric acid produced, 0.6t of low-pressure saturated steam can be generated.

[0162] The first SO3 circulation absorption system acid side process is as follows: 99% sulfuric acid is sprayed into the upper part of the first absorption tower 21 to react with the 300°C process gas sent from the lower part of the tower to generate high-temperature and highly concentrated sulfuric acid (temperature 215°C, concentration 99.4%) at the bottom of the tower. The high-temperature and highly concentrated sulfuric acid enters the first absorption acid circulation tank 22. It is then pressurized and sent to the evaporator 24 by the first absorption acid circulation acid pump 23, and heat exchanged with the low-pressure feed water to produce 0.8MPa(g) low-pressure saturated steam. The acid temperature is reduced to 190°C, and then most of the sulfuric acid is sent to the mixer 25. The concentration is adjusted to 99% by the dilution water at the outlet of the jet water pump 46. The sulfuric acid temperature is raised to 195°C. The sulfuric acid discharged from the mixer 25 enters the upper part of the first absorption tower 21 to circulate and react with the process gas; another part of the sulfuric acid (temperature 190°C) is discharged from the evaporator 24. , concentration 99.4%) respectively enter the low-pressure feed water heater 41 and the low-pressure evaporator 42 of the acid series waste heat recovery unit, and part of the sulfuric acid (temperature 190°C, concentration 99.4%) is sent to the low-pressure feed water for heat exchange with the low-pressure feed water pump 45, and the acid temperature is reduced to 140°C. The other part of the sulfuric acid (temperature 190°C, concentration 99.4%) is sent to the low-pressure evaporator 42 to heat the desalted water (or condensed water) to produce low-pressure steam, and the acid temperature is also reduced to 140°C. The sulfuric acid at the outlet of the low-pressure feed water heater 41 is combined with the sulfuric acid at the outlet of the low-pressure evaporator 42 and then enters the first SO3 absorption acid desalted water cooler 44 to exchange heat with the desalted water (or condensed water), and the acid temperature is reduced to 90°C. It is sent to the air drying acid circulation tank 12- of the air drying circulation system to adjust the acid concentration of the air drying circulation system.

[0163] Example 6

[0164] See Fig.11

[0165] The temperature of the desalted water (or condensed water) sent into the boundary area is 50°C, so the desalted water (or condensed water) can be directly sent to the water side inlet of the second SO3 absorption acid desalted water cooler 34, and the same steam production effect can be obtained by using steps 2 and 3 of the above embodiment. The air drying acid circulation system can use the existing circulating water cooling solution.

[0166] It should be noted that each step of the above-mentioned application embodiments can replace the corresponding steps of other embodiments to form a new embodiment, and the above-mentioned embodiments are all within the scope of protection of this patent.

Claims

1. A method for drying and absorbing high-efficiency waste heat recovery in sulfuric acid production from sulfur, characterized in that: All the desalted water or condensed water required by the high-temperature waste heat recovery system and the low-temperature waste heat recovery system in the sulfuric acid-making device are heat exchanged with sulfuric acid in the air drying circulation system and the second SO3 circulation absorption system in turn to recover the process waste heat of the above two circulation systems, and then the desalted water or condensed water after heat exchange and temperature increase is sent to the first SO3 circulation absorption system acid series waste heat recovery unit to produce 0.2±0.1MPa low-pressure steam, and then the generated low-pressure steam is sprayed into the SO3-containing primary conversion process gas at the inlet of the first SO3 circulation absorption system, and the reaction heat of the low-pressure steam and SO3 chemical reaction to generate sulfuric acid is used to increase the thermal energy of the low-pressure steam to the thermal energy of the higher temperature process gas. As the process gas after the reaction enters the first SO3 circulation absorption system, this part of the 0.2±0.1MPa low-pressure steam The thermal energy finally generates an equal amount of (0.8±0.4MPa(g) low-pressure steam in the evaporator of the first SO3 circulation absorption system.

2. The method according to claim 1, characterized in that The steps of this method are as follows: 1) Normal temperature desalted water or condensed water enters the air drying acid desalted water cooler, recovers the heat in the air drying acid circulation process, and heats the desalted water (or condensed water) to 40±10℃; 2) The desalted water or condensed water at the outlet of the air drying acid desalted water cooler is then sent to the second SO3 absorption acid desalted water cooler to recover the heat in the second absorption cycle process and heat the desalted water or condensed water to 65±10°C; 3) The desalted water or condensed water at the outlet of the second SO3 absorption acid desalted water cooler is then sent to the first SO3 absorption acid desalted water cooler to recover the 120±20℃ heat of the high-temperature acid sent out of the first absorption cycle, and the temperature of the desalted water or condensed water is heated to 85±10℃. The high-temperature acid of 170±25℃ is then used to generate 0.2±0.1MPa low-pressure steam in the low-pressure evaporator or low-pressure evaporator, and then these low-pressure steams are sprayed into the primary conversion process gas entering the first absorption tower. The SO3 in the process gas reacts with the low-pressure steam to generate sulfuric acid. At the same time, the low-temperature heat of the low-pressure steam is also converted into the heat of the higher temperature process gas 280±40℃. This part of heat is absorbed by the circulating acid along with the absorption reaction in the first absorption tower, so that the temperature of the circulating acid is further increased, and the high-temperature circulating acid generates an equal amount of 0.8±0.4MPa(g) low-pressure saturated steam in the evaporator of the first SO3 circulation absorption system.

3. A device for implementing the method of claim 1, characterized in that: The device comprises an air drying circulation system, a second SO3 circulation absorption system, and a first SO3 circulation absorption system, wherein the first SO3 circulation absorption system is provided with an acid preheating recovery unit; The desalted water or condensed water enters the air drying acid desalted water cooler (14) of the air drying circulation system for heat exchange, and the air drying acid desalted water cooler (14) is located on the output pipeline at the bottom of the air drying tower; The desalted water or condensed water from the air-dried acid desalted water cooler (14) enters the second SO3 absorption acid desalted water cooler (34) of the second SO3 circulation absorption system for heat exchange, and the second SO3 absorption acid desalted water cooler (34) is located on the output pipeline at the bottom of the second absorption tower; The desalted water coming out of the second SO3 absorption acid desalted water cooler (34) enters the acid-chain waste heat recovery unit of the first SO3 circulation absorption system for heat exchange. The acid-chain waste heat recovery unit obtains low-pressure steam, low-pressure feed water and dilution water respectively. The steam output end of the low-pressure steam is connected to the output end of the primary conversion process gas, the output end of the low-pressure feed water is connected to the evaporator, and the output end of the absorption water is connected to the mixer.

4. The device according to claim 3, characterized in that An air drying circulation system is provided with an air drying tower, and an air drying acid circulation tank (12), an air drying circulation acid pump (13) and an air drying acid desalted water cooler (14) are sequentially provided on a pipeline at an output end at the bottom of the air drying tower, and part of the sulfuric acid output from the air drying acid desalted water cooler (14) is circulated into the top of the air drying tower (11); Preferably: another part of the sulfuric acid is used as the acid for the second SO3 circulation absorption system; and the air-dried acid circulation tank (12) is also provided with an acid input terminal from the first SO3 circulation absorption system.

5. The device according to claim 3, characterized in that An air drying tower is provided in the air drying circulation system. An air drying acid desalted water cooler (14), an air drying acid circulation tank (12) and an air drying circulation acid pump (13) are sequentially provided on a pipeline at an output end at the bottom of the air drying tower. Part of the sulfuric acid output from the air drying circulation acid pump (13) is circulated into the top of the air drying tower (11). Preferably: another part of the sulfuric acid is used as the acid for the second SO3 circulation absorption system; and the air-dried acid circulation tank (12) is also provided with an acid input terminal from the first SO3 circulation absorption system.

6. The device according to claim 3, characterized in that A second absorption tower (31) is provided in the second SO3 circulation absorption system. A second absorption acid circulation tank (32), a second absorption acid circulation acid pump (33) and a second SO3 absorption acid desalted water cooler (34) are provided in sequence on the pipeline output from the bottom of the second absorption tower (31). Part of the sulfuric acid discharged from the second SO3 absorption acid desalted water cooler enters the top of the second absorption tower. Preferably, another part of the sulfuric acid is output as a sulfuric acid product or as a string acid for the air drying circulation system, and the second absorption acid circulation tank (32) is also provided with a string acid input end from the air drying circulation system.

7. The device according to claim 3, characterized in that A second absorption tower (31) is provided in the second SO3 circulation absorption system. A second SO3 absorption acid desalted water cooler (34), a second absorption acid circulation tank (32) and a second absorption acid circulation acid pump (33) are provided in sequence on the pipeline output from the bottom of the second absorption tower (31). Part of the sulfuric acid output from the second absorption acid circulation acid pump (33) enters the top of the second absorption tower. Preferably, another part of the sulfuric acid is output as a sulfuric acid product or as a string acid for the air drying circulation system, and the second absorption acid circulation tank (32) is also provided with a string acid input end from the air drying circulation system.

8. The device according to claim 3, characterized in that A first absorption tower (21) is provided in the first SO3 circulation absorption system, and the bottom of the first absorption tower (21) is connected to the first absorption acid circulation tank (22), the first absorption acid circulation acid pump (23) and the evaporator (24) in sequence. One output end of the evaporator (24) is connected to the upper part of the first absorption tower (21) through a mixer (25), and the other output end is connected to a series acid waste heat recovery unit. The low-pressure steam generated by the series acid waste heat recovery unit is connected to the output pipeline of the primary conversion process gas, the low-pressure feed water output end generated by the series acid waste heat recovery unit is connected to the evaporator (24), and the dilution water output end generated by the series acid waste heat recovery unit is connected to the mixer (25).

9. The device according to claim 8, characterized in that The acid-binding waste heat recovery unit comprises a low-pressure feedwater heater (41) and a low-pressure evaporator (42); the acid-binding output pipeline from the first SO3 circulation absorption system is connected to the low-pressure feedwater heater (41), the low-pressure evaporator (42) and the first SO3 absorption acid desalted water cooler (44) in sequence; the sulfuric acid output end of the first SO3 absorption acid desalted water cooler (44) is connected to the air drying acid circulation tank (12) of the air drying circulation system; The desalted water output from the second SO3 circulation absorption system passes through the first SO3 absorption acid desalted water cooler (44) and is connected to the low-pressure evaporator (42). The low-pressure evaporator (42) is provided with a low-pressure steam output end, a dilution water output end and a low-pressure feed water output end. The low-pressure feed water output end is connected to the evaporator (24) through a low-pressure feed water pump (45) and a low-pressure feed water heater (41) in turn. The dilution water output end is connected to the mixer (25) through a jet water pump (46). The low-pressure steam output end is connected to the output end of the primary conversion process gas.

10. The device according to claim 8, characterized in that: The acid-binding waste heat recovery unit comprises a low-pressure feedwater heater (41) and a low-pressure evaporator (42); the acid-binding output pipeline from the first SO3 circulation absorption system is connected to the low-pressure feedwater heater (41), the low-pressure evaporator (42) and the first SO3 absorption acid desalted water cooler (44) in sequence; the sulfuric acid output end of the first SO3 absorption acid desalted water cooler (44) is connected to the air drying acid circulation tank (12) of the air drying circulation system; The desalted water output from the second SO3 circulation absorption system is connected to the first SO3 absorption acid desalted water cooler (44), one output of the first SO3 absorption acid desalted water cooler (44) is connected to the low-low pressure evaporator (42), and the low-low pressure evaporator (42) is provided with an output end of low-low pressure steam; the other output end is connected to the deaerator (43), the dilution water output end of the deaerator (43) is connected to the mixer (25) through the jet water pump (46), the low-pressure feed water output end of the deaerator (43) is connected to the evaporator (24) through the low-pressure feed water pump (45) and the low-pressure feed water heater (41), and the low-low pressure steam output end of the deaerator (43) is connected to the low-low pressure steam output end of the low-low pressure evaporator (42).

11. The device according to claim 8, characterized in that The acid waste heat recovery unit comprises a low-pressure feedwater heater (41) and a low-pressure evaporator (42). The acid output pipeline from the first SO3 circulation absorption system is connected to the low-pressure feedwater heater (41) and the low-pressure evaporator (42) respectively. The sulfuric acid output ends of the low-pressure feedwater heater (41) and the low-pressure evaporator (42) are both connected to the first SO3 absorption acid desalted water cooler (44). The sulfuric acid output end of the first SO3 absorption acid desalted water cooler (44) is connected to the air drying acid circulation tank (12) of the air drying circulation system. The desalted water output from the second SO3 circulation absorption system passes through the first SO3 absorption acid desalted water cooler (44) and is connected to the low-pressure evaporator (42). The low-pressure evaporator (42) is provided with a low-pressure steam output end, a dilution water output end and a low-pressure feed water output end. The low-pressure feed water output end is connected to the evaporator (24) through a low-pressure feed water pump (45) and a low-pressure feed water heater (41) in turn, and the dilution water output end is connected to the mixer (25) through a jet water pump (46).

12. The device according to claim 8, characterized in that The acid waste heat recovery unit comprises a low-pressure feedwater heater (41) and a low-pressure evaporator (42). The acid output pipeline from the first SO3 circulation absorption system is connected to the low-pressure feedwater heater (41) and the low-pressure evaporator (42) respectively. The sulfuric acid output ends of the low-pressure feedwater heater (41) and the low-pressure evaporator (42) are both connected to the first SO3 absorption acid desalted water cooler (44). The sulfuric acid output end of the first SO3 absorption acid desalted water cooler (44) is connected to the air drying acid circulation tank (12) of the air drying circulation system. The desalted water output from the second SO3 circulation absorption system is connected to the first SO3 absorption acid desalted water cooler (44), one output of the first SO3 absorption acid desalted water cooler (44) is connected to the low-low pressure evaporator (42), and the low-low pressure evaporator (42) is provided with an output end of low-low pressure steam; the other output end is connected to the deaerator (43), the dilution water output end of the deaerator (43) is connected to the mixer (25) through the jet water pump (46), the low-pressure feed water output end of the deaerator (43) is connected to the evaporator (24) through the low-pressure feed water pump (45) and the low-pressure feed water heater (41), and the low-low pressure steam output end of the deaerator (43) is connected to the low-low pressure steam output end of the low-low pressure evaporator (42).

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