Process and apparatus for producing only high-pressure steam utilizing heat in sulfuric acid production

Abstract

The present invention relates to the technical field of heat utilization, and in particular to a process and apparatus for producing only high-pressure steam utilizing heat in sulfuric acid production. According to the process for producing only high-pressure steam utilizing heat in sulfuric acid production, in sulfuric acid production, the temperature of high-temperature sulfuric acid in a lower section of a low-temperature heat recovery absorption tower is increased, the temperature of the high-temperature sulfuric acid being 240-280ºC, and the high-temperature sulfuric acid exhibits a sufficient temperature difference, so that reaction heat generated by the reaction of SO3 with water to form sulfuric acid in the low-temperature heat recovery absorption tower can be entirely transferred to a high-pressure steam system so as to produce only high-pressure steam and no low-pressure steam. Compared with the prior art, in an existing sulfuric acid production apparatus, by increasing the temperature of an acid in a low-temperature heat recovery system, and by means of heat transfer, only high-pressure steam is produced and low-pressure steam is no longer produced, eliminating the use of a low-pressure steam system, and simplifying a system.

Description

A heat energy utilization process and device for producing high-pressure steam in sulfuric acid production TECHNICAL FIELD

[0001] The present application relates to the technical field of heat energy utilization, in particular to a heat energy utilization process and device for producing high-pressure steam in sulfuric acid production. BACKGROUND

[0002] Currently, whether the heat energy recovery system of the sulfuric acid industry is efficient is the top priority of the entire device. The ton acid steam production of the current sulfur-burning sulfuric acid device is 1.25-1.32 t / t acid in high-pressure steam of 3.0-9.8 MPa, 400-540 DEG C, with a low-temperature heat recovery system, abbreviated as HRS (Heat Recovery Systems), which can produce 0.6-1.0 MPa low-pressure saturated steam ~ 0.45 t / t acid. The price difference between the two kinds of steam is large in the market, so it is urgent to improve the production of high-pressure steam to generate more economic benefits in the sulfuric acid industry.

[0003] A Chinese patent with application number CN2024105933155 discloses a device that can produce more high-pressure steam by flexibly configuring three sets of heat exchangers according to the use scenario and object to utilize the heat in sulfuric acid production as much as possible. However, in actual use, it is found that the acid temperature of the lower tower of the HRS tower does not exceed 230 DEG C, the acid temperature is not high enough, and there is not enough temperature difference to transfer the reaction heat of SO3 and water in the HRS tower to generate sulfuric acid into the high-pressure steam system. Only part of the low-pressure steam can be produced, and it is impossible to produce all high-pressure steam. 3 SUMMARY

[0004] The present application overcomes the shortcomings of the prior art and provides a heat energy utilization process and device for producing high-pressure steam in sulfuric acid production. The heat of the low-pressure steam produced by the existing low-temperature heat recovery system is transferred and all high-pressure steam is produced, without producing low-pressure steam, reducing the low-pressure steam system, and generating more economic benefits.

[0005] To achieve the above-mentioned purpose, a heat energy utilization process for producing high-pressure steam in sulfuric acid production is designed. The temperature of the high-temperature sulfuric acid in the lower tower of the low-temperature heat recovery absorption tower is increased in sulfuric acid production. The temperature of the high-temperature sulfuric acid is 240-280 DEG C. The high-temperature sulfuric acid has enough temperature difference to transfer the reaction heat of SO3 and water in the low-temperature heat recovery absorption tower to generate sulfuric acid to the high-pressure steam system, and all high-pressure steam is produced without producing low-pressure steam.

[0006] The high-temperature sulfuric acid in the lower tower of the low-temperature heat recovery absorption tower is used as a direct or indirect heat source for high-pressure heaters, flue gas heaters, and air heaters, respectively.

[0007] ​The air heater heats the air to be incinerated, and the heated air is incinerated to provide heat for the high-pressure steam system;

[0008] The flue gas heater heats the flue gas from the low-temperature heat recovery absorption tower, and the flue gas from the low-temperature heat recovery absorption tower is heated to enter the cold-heat heat exchanger. The heat of the flue gas at the other side of the outlet of the cold-heat heat exchanger is transferred to the high-pressure steam system through the economizer 3A and the economizer 3B.

[0009] The high-pressure heater heats the feed water from the economizer 3A and the economizer 4A in the high-pressure steam system. The heated water enters the economizer 3B and the economizer 4B in the high-pressure steam system to be heated again to obtain high-pressure steam.

[0010] The heated water also passes through the heating of the waste heat boiler, the superheater 4A and the superheater 1B to obtain high-pressure steam. The flue side inlet and outlet of the waste heat boiler are arranged between the incineration unit and the conversion unit. The superheater 4A is arranged between the conversion unit and the secondary absorption unit. The superheater 1B is arranged in the conversion unit.

[0011] The temperature of the sulfuric acid at the lower tower of the low-temperature heat recovery absorption tower is 240-280℃. The air heater heats the air entering the incinerator to heat the air from 60~130℃ to 220~260℃. The flue gas heater heats the flue gas from the low-temperature heat recovery absorption tower to heat the flue gas from 70~90℃ to 200~250℃ to enter the cold-heat heat exchanger. The high-pressure heater heats the high-pressure feed water entering the economizer 3A and the economizer 4A to heat the high-pressure feed water from 104℃~170℃ to 200~260℃.

[0012] The flue gas heater includes a flue gas heater A and a flue gas heater B. The high-temperature sulfuric acid at the lower tower of the low-temperature heat recovery absorption tower enters the high-pressure heater, the flue gas heater B and the air heater. The temperature of the sulfuric acid from the high-pressure heater, the flue gas heater B and the air heater is reduced, and the sulfuric acid is heated in the flue gas heater A to provide heat. The flue gas heater A and the flue gas heater B heat the flue gas from the low-temperature heat recovery absorption tower twice.

[0013] The flue gas from the low-temperature heat recovery absorption tower is heated first in the flue gas heater A to heat the flue gas from 70~90℃ to 150±20℃, and then the flue gas is heated second in the flue gas heater B to heat the flue gas to 200~250℃ to enter the cold-heat heat exchanger.

[0014] The low-temperature heat recovery absorption tower, the air heater, the flue gas heater and the high-pressure heater are provided with temperature monitoring points and control valves. The amount of material entering the equipment is adjusted according to the set temperature parameters to control the temperature.

[0015] The material in contact with high-temperature sulfuric acid in the low-temperature heat recovery absorption tower, air heater, flue gas heater and high-pressure heater is selected from acid-resistant stainless steel, and the material in contact with hot water and steam is selected from carbon steel.

[0016] The sulfuric acid production process includes, but is not limited to, sulfuric acid production, pyrite acid production and smelting flue gas acid production.

[0017] To achieve the above-mentioned purpose, a heat energy utilization device for producing high-pressure steam in the sulfuric acid production is designed, the acid side outlet of the low-temperature heat recovery absorption tower is divided into several paths, and is respectively connected with the acid side inlet of the high-pressure heater, flue gas heater B and air heater; the acid side outlets of the high-pressure heater, flue gas heater B and air heater are gathered into two paths, and are respectively connected with the inlet of the diluter of the low-temperature heat recovery absorption tower and the acid side inlet of the flue gas heater A; the outlet of the diluter of the low-temperature heat recovery absorption tower is connected with the low-temperature heat recovery absorption tower, the acid side outlet of the flue gas heater A is connected with the acid side inlet of the preheater, and the acid side outlet of the preheater is respectively connected with the secondary absorption unit and the drying unit; in the high-pressure steam system, the water side inlet of the preheater is connected with a desalted water source, the water side outlet of the preheater is connected with the inlet of the deaerator, the outlet of the deaerator is respectively connected with the water side inlet of the economizer 3A, the water side inlet of the economizer 4A, the diluter dilution water pipeline and the boiler dosing device through the boiler feed water pump; the water side outlet of the economizer 3A and the water side outlet of the economizer 4A are gathered into one path, and are jointly connected with the water side inlet of the high-pressure heater; the water side outlet of the high-pressure heater is divided into two paths, and is respectively connected with the water side inlet of the economizer 3B and the water side inlet of the economizer 4B; the water side outlet of the economizer 3B and the water side outlet of the economizer 4B are gathered into one path, and are jointly connected with the water side inlet of the waste heat boiler; the steam side outlet of the waste heat boiler is connected with the steam side inlet of the superheater 4A; the steam side outlet of the superheater 4A is connected with the steam side inlet of the superheater 1B; and the steam side outlet of the superheater 1B produces high-pressure steam.

[0018] Compared with the prior art, in the existing sulfuric acid production device, the acid temperature of the low-temperature heat recovery system is increased, high-pressure steam is produced through heat transfer, low-pressure steam is no longer produced, the low-pressure steam system is cancelled, and the system is simplified. BRIEF DESCRIPTION OF DRAWINGS

[0019] Fig. 1 is a process flow diagram of the flue gas and acid system in the sulfuric acid production process.

[0020] Fig. 2 is a process flow diagram of water and steam in the sulfuric acid production process.

[0021] Referring to Figures 1 and 2, 1-1 is an air filter, 1-2 is a drying tower, 1-3 is a main fan, 1-4 is an air heater, 1-5 is a sulfur incinerator, 1-6 is a waste heat boiler, 1-7 is a converter, 1-8 is a high-temperature superheater 1B, 1-9 is a hot-to-hot heat exchanger, 1-10 is a cold-to-hot heat exchanger, 1-11 is an economizer 3B, 1-12 is an economizer 3A, 1-13 is a low-temperature heat recovery absorption tower, 1-14 is a flue gas heater, 1-14-1 is a flue gas heater A, 1-14-2 is a flue gas heater B, 1-15 is a superheater 4A, 1-16 is an economizer 4B, 1-17 is an economizer 4A, 1-18 is a secondary absorption tower, 1-19 is a secondary absorption acid pump tank, 1-20 is a secondary absorption acid cooler, 1-21 is a finished acid cooler, and 1-22 is finished acid. 1-23 is the acid circulation pump, 1-24 is the high-pressure heater, 1-25 is the low-temperature heat recovery absorption tower diluent, 1-26 is the preheater, 1-27 is the dry acid pump tank, 1-28 is the dry acid cooler, 1-29 is the demineralized water (0.4 MPa), 1-30 is the deaerator, 1-31 is the continuous blowdown expander, 1-32 is the periodic blowdown expander, 1-34 is the vent, 1-35 is the drain outlet, 1-36 is the low-pressure steam, 1-37 is the boiler feed water pump, 1-38 is the boiler chemical dosing device, 1-39 is the high-pressure steam, 1-40 is the liquid sulfur, 1-41 is the air, 1-42 is the tail suction device, 1-43 is the pump tank dilution water, and 1-44 is the HRS dilution water. The numbers in the diamond-shaped boxes indicate the flow direction of flue gas, acid, water, and steam in the sulfuric acid production process of this invention. Detailed Implementation

[0022] The present invention will now be further described with reference to the accompanying drawings. Example 1

[0023] As shown in Figures 1 and 2, in the sulfuric acid production process of this embodiment, the low-temperature heat recovery absorption tower 1-13 increases the temperature of the high-temperature sulfuric acid in the lower tower. The temperature of the high-temperature sulfuric acid is 240-280℃. This sufficient temperature difference allows the high-temperature sulfuric acid to effectively utilize the SO₂ in the low-temperature heat recovery absorption tower 1-13. 3 The heat generated during the reaction with water to produce sulfuric acid is entirely transferred to the high-pressure steam system, resulting in the production of high-pressure steam without the generation of low-pressure steam.

[0024] The high-temperature sulfuric acid in the lower part of the low-temperature heat recovery absorption tower 1-13 is used as the direct or indirect heat source for the high-pressure heater 1-24, the flue gas heater 1-14, and the air heater 1-4, respectively.

[0025] Air heaters 1-4 heat the air to be burned. After heating, the air is mixed with sulfur and burned to provide heat for the high-pressure steam system.

[0026] The flue gas heater 1-14 heats the flue gas from the low-temperature heat recovery absorption tower 1-13, and the flue gas heated by the low-temperature heat recovery absorption tower 1-13 enters the cold-heat heat exchanger 1-10 and exchanges heat with the flue gas on the other side of the cold-heat heat exchanger, and the heat of the flue gas at the outlet of the cold-heat heat exchanger 1-10 on the other side is transferred to the high-pressure steam system through the coal economizer 3A 1-12 and the coal economizer 3B 1-11.

[0027] The high-pressure heater 1-24 heats the feed water from the coal economizer 3A 1-12 in the high-pressure steam system and the coal economizer 4A 1-17, and the heated water enters the coal economizer 3B 1-11 and the coal economizer 4B 1-16 in the high-pressure steam system again to be heated, and the heated water (No. 118) also passes through the heating of the waste heat boiler 1-6, the superheater 4A 1-15 and the superheater 1B 1-8 to obtain high-pressure steam (No. 121), and the flue side inlet and outlet of the waste heat boiler 1-6 are arranged between the incineration unit and the conversion unit, the superheater 4A is arranged between the conversion unit and the secondary absorption unit, and the superheater 1B is arranged in the conversion unit.

[0028] The temperature of sulfuric acid at the lower tower of the low-temperature heat recovery absorption tower 1-13 is 240-280℃, the air heater 1-4 heats the air entering the incineration unit, and the air is heated from 60~130℃ to 220~260℃; the flue gas heater 1-14 heats the flue gas from the low-temperature heat recovery absorption tower 1-13, and the flue gas is heated from 70~90℃ to 200~250℃ and enters the cold-heat heat exchanger 1-10; the high-pressure heater 1-24 heats the high-pressure feed water entering the coal economizer 3A 1-12 and the coal economizer 4A 1-17, and the high-pressure feed water is heated from 104℃~170℃ to 200~260℃.

[0029] The low-temperature heat recovery absorption tower 1-13, the air heater 1-4, the flue gas heater 1-14 and the high-pressure heater 1-24 are provided with temperature monitoring points and control valves after the rear, and the amount of material entering the equipment is adjusted according to the set temperature parameters to control the temperature.

[0030] The materials in contact with high-temperature sulfuric acid in the low-temperature heat recovery absorption tower 1-13, the air heater 1-4, the flue gas heater 1-14 and the high-pressure heater 1-24 are selected from acid-resistant stainless steel, and the materials in contact with hot water and steam are selected from carbon steel.

[0031] The sulfuric acid production process includes but is not limited to sulfuric acid production from sulfur, sulfuric acid production from pyrite, and sulfuric acid production from smelting flue gas.

[0032] In the production of sulfuric acid, air is filtered through air filter 1-1, the filtered air is dried in drying tower 1-2, then the dried air is pressurized by fan 1-3 and heated by air heater 1-4 and enters sulfur-burning furnace 1-5, burns and reacts with liquid sulfur in sulfur-burning furnace 1-5 to generate high-temperature SO2-containing flue gas, the SO2-containing flue gas enters waste heat boiler 1-6 to transfer the high-temperature heat in the flue gas to the high-pressure steam system, and high-pressure steam is generated by the high-pressure feed water in waste heat boiler 1-6, the SO2-containing flue gas after coming out of waste heat boiler 1-6 enters converter 1-7 for catalytic oxidation, the flue gas after the first catalytic oxidation in converter 1-7 enters superheater 1B 1-8 to transfer heat to the high-pressure steam in superheater 1B, the flue gas after cooling enters converter 1-7 for the second catalytic oxidation, the flue gas after the second catalytic oxidation in converter 1-7 enters heat heat exchanger 1-9 to transfer heat to the flue gas on the other side of heat heat exchanger 1-9, the flue gas after cooling enters converter 1-7 for the third catalytic oxidation, the flue gas after the third catalytic oxidation in converter 1-7 enters cold heat exchanger 1-10, economizer 3A and economizer 3B, the heat in the flue gas is transferred to the high-pressure feed water in economizer 3A and economizer 3B, the flue gas after cooling enters low-temperature heat recovery absorption tower 1-13 for SO3 absorption, the flue gas after coming out of low-temperature heat recovery absorption tower 1-13 enters converter 1-7 for the fourth catalytic oxidation after passing through flue gas heater 1-14, cold heat exchanger 1-10 and heat heat exchanger 1-9, the flue gas after the fourth catalytic oxidation in converter 1-7 enters superheater 4A, economizer 4B and economizer 4A to transfer the high-temperature heat in the flue gas to the high-pressure steam and feed water in superheater 4A, economizer 4B and economizer 4A, and the flue gas after cooling enters two absorption tower 1-18 for secondary SO3 absorption.

[0033] The high-temperature sulfuric acid after coming out of low-temperature heat recovery absorption tower 1-13 is combined after passing through air heater 1-4, flue gas heater 1-14 and high-pressure heater 1-24, and then is divided into two paths, one path enters flue gas heater A, preheater and then enters two absorption acid pump tank 1-19, and then passes through finished acid cooler 1-21 to obtain finished acid 1-22, and the other path of high-temperature sulfuric acid passes through low-temperature heat recovery absorption tower diluter 1-25, is diluted by adding water and serially diluted acid, and then returns to low-temperature heat recovery absorption tower 1-13 to repeat the absorption process.

[0034] The acid side outlet of the low-temperature heat recovery absorption tower 1-13 is connected to the acid side inlet of the high-pressure heater 1-24, the flue gas heater 1-14 and the air heater 1-4 through the acid circulating pump 1-23, respectively; the acid side outlets of the high-pressure heater 1-24, the flue gas heater 1-14 and the air heater 1-4 are connected to the inlet of the low-temperature heat recovery absorption tower diluter 1-25 after being converged, and the outlet of the low-temperature heat recovery absorption tower diluter 1-25 is connected to the low-temperature heat recovery absorption tower 1-13. The acid side outlet of the flue gas heater 1-14 is connected to the acid side inlet of the preheater 1-26, and the acid side outlet of the preheater 1-26 is connected to the secondary absorption unit and the drying unit, respectively.

[0035] The drying unit includes, but is not limited to, an air filter 1-1, a drying tower 1-2, one end of the air filter 1-1 being connected to an air source, the other end of the air filter 1-1 being connected to the drying tower 1-2, the outlet of the drying tower 1-2 being connected to the inlet of a fan 1-3, the outlet of the fan 1-3 being connected to a burning unit through an air heater 1-4; the burning unit includes, but is not limited to, a sulfur burning furnace 1-5, a waste heat boiler 1-6, the outlet of the main fan 1-3, a liquid sulfur source being connected to the inlet of the sulfur burning furnace 1-5, the outlet of the sulfur burning furnace 1-5 being connected to the flue gas side inlet of the waste heat boiler 1-6, the flue gas side outlet of the waste heat boiler 1-6 being connected to a conversion unit, the conversion unit including, but not limited to, a converter 1-7, a hot heat exchanger 1-9, a cold heat exchanger 1-10, the flue gas side outlet of the waste heat boiler 1-6 being connected to the inlet of the first stage of the converter 1-7, the outlet of the first stage of the converter 1-7 being connected to the flue gas side inlet of a superheater 1B1-8, the flue gas side outlet of the superheater 1B being connected to the inlet of the second stage of the converter 1-7, the outlet of the second stage of the converter 1-7 being connected to the first inlet of the hot heat exchanger 1-9, the first outlet of the hot heat exchanger 1-9 being connected to the inlet of the third stage of the converter 1-7, the third stage outlet of the converter 1-7 being connected to the first inlet of the cold heat exchanger 1-10, the first outlet of the cold heat exchanger 1-10 being connected to the flue gas side inlet of an economizer 3B, the flue gas side inlet of the economizer 3B being connected to the flue gas side inlet of an economizer 3A, the flue gas side outlet of the economizer 3A being connected to a primary absorption unit, the primary absorption unit including, but not limited to, a low-temperature heat recovery absorption tower 1-13, an acid circulating pump 1-23, the flue gas side outlet of the economizer 3A being connected to the flue gas inlet of the low-temperature heat recovery absorption tower 1-13, the flue gas outlet of the low-temperature heat recovery absorption tower 1-13 being connected to the conversion unit; the flue gas outlet of the low-temperature heat recovery absorption tower 1-13 being connected to the flue gas inlet of a flue gas heater 1-14, the flue gas outlet of the flue gas heater 1-14 being connected to the second inlet of the cold heat exchanger 1-10, the second outlet of the cold heat exchanger 1-10 being connected to the second inlet of the hot heat exchanger 1-9, the second outlet of the hot heat exchanger 1-9 being connected to the fourth inlet of the converter 1-7, the fourth outlet of the converter 1-7 being connected to the flue gas side inlet of a superheater 4A, the flue gas side outlet of the superheater 4A being connected to the flue gas side inlet of an economizer 4B, the flue gas side outlet of the economizer 4B being connected to the flue gas side inlet of the economizer 4A, the flue gas side outlet of the economizer 4A being connected to a secondary absorption unit, the secondary absorption unit including, but not limited to, a secondary absorption tower 1-18, a secondary absorption acid pump tank 1-19, the flue gas side outlet of the economizer 4A being connected to the secondary absorption tower 1-18, the acid side outlet of the secondary absorption tower 1-18 being connected to the inlet of the secondary absorption acid pump tank 1-19, the outlet of the secondary absorption acid pump tank 1-19 being connected to the inlet of a finished acid cooler 1-21, the outlet of the finished acid cooler 1-21 obtaining finished acid.

[0036] In the high-pressure steam system, the water side inlet of the preheater 1-26 is connected to a desalted water source, the water side outlet of the preheater 1-26 is connected to the inlet of the deaerator 1-30, the outlet of the deaerator 1-30 is connected to the boiler dosing device 1-38, the water side inlet of the economizer 3A, the water side inlet of the economizer 4A, and the dilution water pipeline 1-32 of the diluter through the boiler feed water pump 1-37, respectively; the water side outlet of the economizer 3A and the water side outlet of the economizer 4A are merged into one, and are jointly connected to the water side inlet of the high-pressure heater 1-24, the water side outlet of the high-pressure heater 1-24 is divided into two, and is connected to the water side inlet of the economizer 3B and the water side inlet of the economizer 4B, respectively, the water side outlet of the economizer 3B and the water side outlet of the economizer 4B are merged into one, and are jointly connected to the water side inlet of the waste heat boiler 1-6, the steam side outlet of the waste heat boiler 1-6 is connected to the steam side inlet of the superheater 4A, the steam side outlet of the superheater 4A is connected to the steam side inlet of the superheater 1B, and the steam side outlet of the superheater 1B produces high-pressure steam 121.

[0037] The acid side outlet of the preheater 1-26 is connected to the inlet of the dry acid pump tank 1-27 and the inlet of the double absorption acid pump tank 1-19, respectively, the outlet of the dry acid pump tank 1-27 is connected to the inlet of the double absorption acid pump tank 1-19 and the inlet of the low-temperature heat recovery absorption tower diluter 1-25, respectively, the outlet of the double absorption acid pump tank 1-19 is connected to the inlet of the double absorption acid cooler 1-20, and the outlet of the double absorption acid cooler 1-20 is connected to the inlet of the low-temperature heat recovery absorption tower 1-13 and the inlet of the double absorption tower 1-18, respectively.

[0038] The outlet of the dry acid pump tank 1-27 is also connected to the inlet of the dry acid cooler 1-28, the outlet of the dry acid cooler 1-28 is connected to the acid inlet of the drying tower 1-2, and the acid outlet of the drying tower 1-2 is connected to the dry acid pump tank 1-27.

[0039] In this embodiment, the low-temperature heat recovery absorption tower 1-13 is raised from about 200°C in the traditional low-temperature heat recovery system to 220-260°C through high-temperature acid circulation (serial number 72), and the sulfuric acid temperature of the lower tower (serial number 63) is changed from less than 230°C in the traditional process to 240-280°C.

[0040] The air heater 1-4 heats the air entering the sulfur incinerator 1-5 from 60-130°C to 220-260°C, the heated air enters the sulfur incinerator 1-5, the flue gas after the combustion reaction enters the waste heat boiler 1-6, and the high-temperature heat in the flue gas is transferred to the high-pressure steam system in the water vapor of the waste heat boiler 1-6 (i.e. serial number 118 in FIG. 2), to generate more high-pressure steam.

[0041] The flue gas heater 1-14 heats the flue gas (No. 18) from the low-temperature heat recovery absorption tower 1-13 from 70~90℃ to 200~250℃, and the heated flue gas (No. 20) enters the cold-heat heat exchanger 1-10 to exchange heat with the flue gas (No. 14) from the third outlet of the converter 1-7 to further increase the temperature to about 330℃ (No. 21), and then enters the hot-heat heat exchanger 1-9 to exchange heat, and the flue gas (No. 22) meeting the process requirements enters the fourth section of the converter. The flue gas (No. 14) from the third outlet of the converter 1-7 has a temperature of 450~470℃, and the flue gas (No. 15) after heat exchange in the cold-heat heat exchanger 1-10 has a temperature of about 310~350℃, and in the traditional process, the temperature at this point is usually about 250~280℃, which is 60~100℃ higher. The flue gas (No. 20) after heating in the flue gas heater reduces the heat consumption of the flue gas (No. 15) from the cold-heat heat exchanger, and heats the high-pressure hot water through the coal economizer 3A and the coal economizer 3B. The part of the heat that is higher in the improved process than in the traditional process is the heat transferred and utilized from the low-temperature heat source, and this part of the heat is absorbed and utilized through the coal economizer 3A and the coal economizer 3B to generate more high-pressure steam.

[0042] In specific use, the source of the heating medium in the air heater and the flue gas heater is one or more of the high-temperature sulfuric acid generated in the sulfuric acid production process, the high-pressure hot water, the high-pressure steam, and the external heat source.

[0043] The heat source of the high-pressure heater is the high-temperature sulfuric acid generated from the low-temperature heat recovery absorption tower, which enters the heat source medium inlet of the high-pressure heater to exchange heat with the boiler feed water, and then flows out from the heat source medium outlet of the high-pressure heater.

[0044] The high-pressure heater 1-24 heats the boiler feed water (No. 112) from the coal economizer 3A and the coal economizer 4A from 104℃~170℃ to 200~260℃, and then enters the coal economizer 3B and the coal economizer 4B, or enters the coal economizer 3B and the coal economizer 4B after being used as the heat source of the air heater and the flue gas heater. The temperature and the heat of the boiler feed water to the coal economizer are improved, and finally the high-pressure steam production is improved. Example Two

[0045] This example only illustrates the differences from Example One, and the same parts will not be repeated. In this example, the flue gas heater 1-14 includes a flue gas heater A and a flue gas heater B, and the high-temperature sulfuric acid from the lower tower of the low-temperature heat recovery absorption tower 1-13 enters the high-pressure heater 1-24, the flue gas heater B, and the air heater 1-4, respectively. The temperature of the sulfuric acid from the high-pressure heater 1-24, the flue gas heater B, and the air heater 1-4 is reduced, and then the sulfuric acid enters the flue gas heater A to provide heat. The flue gas heater A and the flue gas heater B heat the flue gas from the low-temperature heat recovery absorption tower 1-13 twice.

[0046] The flue gas from the low-temperature heat recovery absorption tower 1-13 is heated to 150±10℃ by the flue gas heater A for the first time, and then heated to 200~250℃ by the flue gas heater B for the second time, and then enters the cold-heat heat exchanger 1-10.

[0047] The acid side outlet of the low-temperature heat recovery absorption tower 1-13 is divided into three parts, which are connected to the acid side inlets of the high-pressure heater 1-24, the flue gas heater B and the air heater 1-4 respectively. The acid side outlets of the high-pressure heater 1-24, the flue gas heater B and the air heater 1-4 are gathered into two parts, which are connected to the inlets of the low-temperature heat recovery absorption tower diluter 1-25 and the acid side inlet of the flue gas heater A respectively. The outlet of the low-temperature heat recovery absorption tower diluter 1-25 is connected to the low-temperature heat recovery absorption tower 1-13. The acid side outlet of the flue gas heater A is connected to the acid side inlet of the preheater 1-26. The acid side outlet of the preheater 1-26 is connected to the secondary absorption unit and the drying unit respectively.

[0048] The present application improves the temperature of the acid in the low-temperature heat recovery absorption tower, which is increased from not more than 230℃ to 240~280℃. The heat in the high-temperature acid is transferred to the high-pressure steam system by the air heater, the flue gas heater and the high-pressure heater. The low-pressure steam part in the traditional low-temperature heat recovery system is cancelled, the purpose of producing all high-pressure steam is achieved, the production of high-pressure steam is significantly improved, and the economic benefit is maximized.

Claims

1. A process for the utilization of heat energy in the production of sulfuric acid for the production of high pressure steam in its entirety, characterized by: In the sulfuric acid production, the temperature of high-temperature sulfuric acid in the lower tower of the low-temperature heat recovery absorption tower (1-13) is increased, the temperature of the high-temperature sulfuric acid is 240-280℃, the high-temperature sulfuric acid has enough temperature difference, and can transfer the reaction heat of SO 3 The reaction heat of the reaction of SO and water to generate sulfuric acid is all transferred to the high-pressure steam system, all high-pressure steam is output, and no low-pressure steam is generated.

2. A process for utilizing heat energy for producing high pressure steam in the production of sulfuric acid according to claim 1, characterized in that: The high-temperature sulfuric acid of the low-temperature heat recovery absorption tower (1-13) is used as a direct or indirect heat source for the high-pressure heater (1-24), the flue gas heater and the air heater (1-4); The air heater (1-4) heats the air to be incinerated, and the heated air is incinerated to provide heat for the high-pressure steam system; The flue gas heater (1-14) heats the flue gas from the low-temperature heat recovery absorption tower (1-13), and the heated flue gas enters the cold-heat heat exchanger (1-10). The heat of the flue gas from the other side of the cold-heat heat exchanger (1-10) is transferred to the high-pressure steam system through the economizer 3A (1-12) and the economizer 3B (1-11). The high-pressure heater (1-24) heats the feed water from the economizer 3A (1-12) and the economizer 4A (1-17) in the high-pressure steam system. The heated water enters the economizer 3B (1-11) and the economizer 4B (1-16) in the high-pressure steam system to be heated, and high-pressure steam (121) is obtained.

3. A process for utilizing heat energy in the production of high pressure steam in the production of sulfuric acid according to claim 1 characterized in that: The heated water also passes through the waste heat boiler (1-6), the superheater 4A (1-15) and the superheater 1B (1-8) to be heated to obtain high-pressure steam (121). The flue side inlet and outlet of the waste heat boiler (1-6) are arranged between the incineration unit and the conversion unit. The superheater 4A (1-15) is arranged between the conversion unit and the secondary absorption unit. The superheater 1B (1-8) is arranged in the conversion unit.

4. A process for utilizing heat energy for producing high pressure steam in sulfuric acid production according to claim 1 characterized in that: The temperature of the sulfuric acid in the lower tower of the low-temperature heat recovery absorption tower (1-13) is 240-280℃. The air heater (1-4) heats the air entering the incinerator to heat the air from 60-130℃ to 220-260℃. The flue gas heater (1-14) heats the flue gas from the low-temperature heat recovery absorption tower (1-13) to heat the flue gas from 70-90℃ to 200-250℃ and enter the cold-heat heat exchanger. The high-pressure heater (1-24) heats the high-pressure feed water entering the economizer 3A (1-12) and the economizer 4A (1-17) to heat the high-pressure feed water from 104-170℃ to 200-260℃.

5. A process for utilizing heat energy in the production of high pressure steam in the production of sulfuric acid according to claim 1 characterized in that: The flue gas heater (1-14) includes a flue gas heater A (1-14-1) and a flue gas heater B (1-14-2). The high-temperature sulfuric acid from the lower tower of the low-temperature heat recovery absorption tower (1-13) enters the high-pressure heater (1-24), the flue gas heater B (1-14-2) and the air heater (1-4). The temperature of the sulfuric acid from the high-pressure heater (1-24), the flue gas heater B (1-14-2) and the air heater (1-4) decreases, and then the sulfuric acid enters the flue gas heater A (1-14-1) to provide heat. The flue gas heater A (1-14-1) and the flue gas heater B (1-14-2) heat the flue gas from the low-temperature heat recovery absorption tower (1-13) twice.

6. A process for utilizing heat energy for producing high pressure steam in sulfuric acid production according to claim 1 characterized in that: The flue gas from the low-temperature heat recovery absorption tower (1-13) is heated for the first time by a flue gas heater A (1-14-1) to heat the flue gas from 70-90℃ to 150±20℃, and then heated for the second time by a flue gas heater B (1-14-2) to heat the flue gas to 200-250℃, and then enters the cold-heat heat exchanger (1-10).

7. A process for utilizing heat energy in the production of high pressure steam in the production of sulfuric acid according to claim 1 characterized in that: The low-temperature heat recovery absorption tower (1-13), the air heater (1-4), the flue gas heater (1-14) and the high-pressure heater (1-24) are all provided with temperature monitoring points and control valves, and the amount of material entering the equipment is adjusted according to the set temperature parameters to control the temperature.

8. A process for utilizing heat energy for producing high pressure steam in sulfuric acid production according to claim 1 characterized in that: The materials in the low-temperature heat recovery absorption tower (1-13), the air heater (1-4), the flue gas heater (1-14) and the high-pressure heater (1-24) that are in contact with high-temperature sulfuric acid are selected from acid-resistant stainless steel, and the materials in contact with hot water and steam are selected from carbon steel.

9. A process for utilizing heat energy in the production of high pressure steam in the production of sulfuric acid according to claim 1 characterized in that: The sulfuric acid production process includes but is not limited to sulfuric acid production from sulfur, sulfuric acid production from pyrite and sulfuric acid production from smelting flue gas.

10. A device for utilizing heat energy for producing high pressure steam in the production of sulfuric acid according to claim 5, characterized in that: The low-temperature heat recovery absorption tower (1-13) has several acid side outlets, which are connected to the acid side inlets of the high-pressure heater (1-24), the flue gas heater B (1-14-2) and the air heater (1-4), respectively; the acid side outlets of the high-pressure heater (1-24), the flue gas heater B (1-14-2) and the air heater (1-4) are gathered into two paths, which are connected to the inlet of the low-temperature heat recovery absorption tower diluter (1-25) and the acid side inlet of the flue gas heater A (1-14-1), respectively; the outlet of the low-temperature heat recovery absorption tower diluter (1-25) is connected to the low-temperature heat recovery absorption tower (1-13), the acid side outlet of the flue gas heater A (1-14-1) is connected to the acid side inlet of the preheater (1-26), and the acid side outlet of the preheater (1-26) is connected to the secondary absorption unit and the drying unit, respectively; in the high-pressure steam system, the water side inlet of the preheater (1-26) is connected to the desalted water source (1-29), the water side outlet of the preheater (1-26) is connected to the inlet of the deaerator (1-30), the outlet of the deaerator (1-30) is connected to the boiler dosing device (1-38), the water side inlet of the economizer 3A (1-12), the water side inlet of the economizer 4A (1-17) and the diluter dilution water pipeline (1-32) through the boiler feed water pump (1-37); the water side outlet of the economizer 3A (1-12) and the water side outlet of the economizer 4A (1-17) are gathered into one path, which is connected to the water side inlet of the high-pressure heater (1-24) together, the water side outlet of the high-pressure heater (1-24) is divided into two paths, which are connected to the water side inlet of the economizer 3B (1-11) and the water side inlet of the economizer 4B (1-16), respectively; the water side outlet of the economizer 3B (1-11) and the water side outlet of the economizer 4B (1-16) are gathered into one path, which is connected to the water side inlet of the waste heat boiler (1-6) together; the steam side outlet of the waste heat boiler (1-6) is connected to the steam side inlet of the superheater 4A (1-15), the steam side outlet of the superheater 4A (1-15) is connected to the steam side inlet of the superheater 1B (1-8), and the steam side outlet of the superheater 1B (1-8) produces high-pressure steam (121).

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