A device and method for solving the problem of excessive production of hydrochloric acid in the process of treating waste liquid of sucralose

Abstract

The present application relates to the harmless treatment field of chemical waste liquid, and particularly discloses a device and method for solving the problem of excessive production of hydrochloric acid in the treatment process of trichloro-sucrose waste liquid, wherein the hydrogen chloride and ammonia gas in the flue gas after denitration are reacted in a gas-gas reactor to generate ammonium chloride, and the by-product of ammonium chloride is separated through heat exchange, trapping and other steps, and the considerable reaction heat is ingeniously used to generate steam for use in the workshop, so that the problems of excessive production of hydrochloric acid and corrosion of the device are solved, the water is used instead of liquid caustic soda in the flue gas purification step, the pollution treatment cost and difficulty are further reduced, and important economic benefits and environmental protection benefits are achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of harmless treatment of chemical waste liquid, and particularly relates to a device and method for solving the problem of excessive production of hydrochloric acid in the treatment process of trichloro sucrose waste liquid. BACKGROUND

[0002] At present, trichloro sucrose (CAS No.: 56038-13-2) is a new type of sweetener, which has the advantages of high sweetness (about 600 times that of sucrose), easy solubility in water, low heat, high safety, and almost no absorption by the human body, and has a very broad market prospect. At present, the method for synthesizing trichloro sucrose in industry is as follows: taking sucrose as raw material, sucrose-6-ethyl ester is prepared by esterification reaction of sucrose, then trichloro sucrose-6-ethyl ester is obtained by chlorination of sucrose-6-ethyl ester, and finally trichloro sucrose is obtained by de-esterification of trichloro sucrose-6-ethyl ester.

[0003] A large amount of waste liquid is generated in the production process of trichloro sucrose, and the chlorine content is about 20%-26%. At present, Shandong Kangbao Biochemical Technology Co., Ltd. uses incineration process to treat trichloro sucrose waste liquid. The trichloro sucrose waste liquid is input into an incinerator for incineration. The flue gas generated by incineration is subjected to cooling, dust removal, denitration and dehydrochlorination. The hydrogen chloride gas is absorbed by water to form hydrochloric acid.

[0004] The incineration process has two problems:

[0005] First, a large amount of hydrogen chloride gas is generated by incineration, which eventually becomes by-product hydrochloric acid. According to the calculation of 20% chlorine content, 100 tons of trichloro sucrose waste liquid incineration will produce 20.56 tons of hydrogen chloride and 68.54 tons of hydrochloric acid (HCl content is 30%). These hydrochloric acids need to be properly treated, otherwise they are easy to pollute the environment.

[0006] Second, the corrosion problem of hydrochloric acid to the device.

[0007] The above problems are the disadvantages of flue gas wet dehydrochlorination, so avoiding flue gas wet dehydrochlorination is the only way to solve the above problems.

[0008] The patent with application No. 202011006202.9 discloses a method for incineration treatment of high-chlorine hazardous waste. By mixing high-chlorine hazardous waste with dechlorination agents such as calcium oxide and magnesium oxide, the chlorine element is fixed in the ash of calcium chloride and magnesium chloride, so as to reduce the content of hydrogen chloride in the flue gas. The purpose of this method is to fix the hydrogen chloride by the dechlorination agent in the incineration stage, but there are still two problems:

[0009] First, the dechlorination agent calcium oxide and magnesium oxide is difficult to be used in the incinerator of trichloro sucrose waste liquid, because the amount of solid calcium oxide or magnesium oxide is too large. Through calculation, 100 tons (chlorine content is 20%) of trichloro sucrose waste liquid needs to input 15.77 tons of calcium oxide or 11.77 tons of magnesium oxide to balance chlorine element, and chlorine element is completely reacted to generate calcium chloride or magnesium chloride. These calcium chloride or magnesium chloride become ash, and the huge treatment amount greatly affects the stable operation of the boiler.

[0010] Second, inorganic chloride is easily reacted with alkaline dechlorination agent to become salt before incineration, and becomes ash after incineration. However, chlorine elements in trichloro sucrose waste liquid are mostly concentrated in molecules, and do not react with alkaline dechlorination agent before incineration. The reactivity of hydrogen chloride gas generated at high temperature during incineration with the alkaline dechlorination agent is very poor, and most of the hydrogen chloride still exists in the flue gas.

[0011] The patent with the application number 200710097522.8 proposes a high-temperature flue gas HCI gas purification technology, which belongs to a dry dehydrochlorination method. Calcium-aluminum-silicon reactants are sprayed into the flue gas in powder form, or are made into a fixed bed of fillers, so that the hydrogen chloride gas in the flue gas can be removed. This method has two problems:

[0012] First, this method belongs to gas-solid reaction, and the reaction efficiency is relatively low. The amount of trichloro sucrose waste liquid incineration flue gas is generally greater than 100,000 cubic meters per hour, and the residence time of hydrogen chloride in the reactor is short, so it is difficult to fully react with the solid dechlorination agent.

[0013] Second, this method belongs to gas-solid reaction, and the dechlorination agent and the generated chloride salt are in solid state. Under the impact of the flue gas speed, the dust is dispersed in the flue gas, which in turn affects the normal operation of the subsequent equipment.

[0014] Shandong Kangbao Biochemical Technology Co., Ltd. found through research that the gas-gas reaction of ammonia and hydrogen chloride can react hydrogen chloride in the flue gas into ammonium chloride. The reaction efficiency is high, the speed is fast, and a considerable amount of heat is released during the reaction process, which can be utilized. One problem to be solved is that the diameter of the reaction product ammonium chloride particles is very small, which becomes aerosol in the flue gas, and needs to be captured and separated from the flue gas. SUMMARY

[0015] The purpose of the present application is to overcome the shortcomings of the prior art, and to provide a device and method for solving the problem of excessive production of hydrochloric acid in the treatment process of trichloro sucrose waste liquid.

[0016] In order to achieve the above purpose, the technical scheme of the present application is as follows: a method for solving the problem of excessive production of hydrochloric acid in the treatment process of trichloro sucrose waste liquid, characterized in that it comprises the following steps:

[0017] (1) Gas-gas reaction: the flue gas after incineration and denitration of trichloro sucrose waste liquid enters the gas-gas reactor with liquid ammonia respectively, hydrogen chloride in the flue gas reacts with ammonia to generate ammonium chloride particles, ammonium chloride particles disperse in the flue gas in the form of aerosol, as the flue gas rises, part of the ammonium chloride particles grow larger, the flue gas passes through the top screen of the gas-gas reactor and enters the heat exchanger tube, ammonium chloride aerosol enters the heat exchanger tube with the flue gas, large particles of ammonium chloride are filtered and settled at the bottom of the gas-gas reactor and discharged for drying treatment to obtain ammonium chloride byproduct;

[0018] (2) Steam generation by flue gas heat exchange: the softened water in the shell side of the heat exchanger is heated by the flue gas to form steam, which enters the steam drum, and the flue gas after heat exchange in the tube side of the heat exchanger enters the collector;

[0019] (3) Ammonium chloride collection: the flue gas is cooled and sprayed in the collector, and the ammonium chloride aerosol in the flue gas is absorbed and settled at the bottom of the collector by the water mist, the spiral scraper agitator in the collector scrapes the wall-adhered ammonium chloride and water paste to the bottom of the collector, the ammonium chloride slurry at the bottom of the collector is discharged for drying treatment to obtain ammonium chloride byproduct, and the flue gas after cooling and removal of ammonium chloride aerosol is discharged through the flue gas outlet of the collector and enters the falling film condenser;

[0020] (4) Falling film condensation: the flue gas is cooled in the falling film condenser, and the gaseous water in the flue gas is condensed into liquid water, and the condensed flue gas enters the packed absorber;

[0021] (5) Flue gas purification: the flue gas entering the packed absorber is absorbed by water circulation to meet the environmental protection emission standard and is discharged to the atmosphere.

[0022] Further, in step (1), the flue gas and liquid ammonia enter the gas-gas reactor tangentially, the liquid ammonia is heated to form ammonia gas after entering the gas-gas reactor, and the flue gas and ammonia gas make spiral motion inside the gas-gas reactor with opposite and staggered rotation to maximize contact.

[0023] Further, in step (1), the flue gas after incineration and denitration of trichloro sucrose waste liquid has a temperature of 180-250℃, and the temperature of the flue gas after reaction rises to 250-300℃ and enters the heat exchanger tube, the reaction of hydrogen chloride and ammonia releases considerable heat (as shown in Table 1), which can cause the temperature of the flue gas to rise.

[0024] Further, in step (2), the pressure of the steam is 0.3-0.6MPa, and the temperature is 133-159℃.

[0025] Further, in step (2), the temperature of the flue gas after heat exchange in the tube side of the heat exchanger is 140-170℃, if the temperature of the flue gas after heat exchange is too low, the gaseous water in the flue gas will condense into liquid and form slurry with ammonium chloride, affecting the operation of the heat exchanger, and if the temperature is too high, the steam production will be correspondingly reduced.

[0026] Further, the temperature of the flue gas discharged from the outlet of the trap in step (3) is 100-120 DEG C, and if the temperature is too low, a large amount of water vapor is condensed into liquid and accumulated at the bottom of the trap, the obtained ammonium chloride slurry is relatively dilute, and the amount of condensed water obtained by the subsequent falling film condenser is relatively small, and if the temperature is too high, the load of the falling film condenser is increased.

[0027] Table 1

[0028] Value Unit Note Daily amount of waste liquid to be incinerated 200.000 t Daily amount of hydrogen chloride to be produced 41.127 t 20% by chlorine content Hydrogen chloride flow rate 1713.615 kg / h Ammonia flow rate 798.122 kg / h Water vapor flow rate 4746.667 kg / h Carbon dioxide flow rate 4913.333 kg / h Oxygen flow rate 675.000 kg / h Nitrogen flow rate 160000.000 kg / h Total flue gas 172846.737 kg / h Reaction heat 14084507.042 kJ Heat of formation of ammonium chloride Specific heat of gas 1.100 kJ / (kg·℃) Temperature rise 74.078 ℃

[0029] The data in Table 1 shows that, in the case of burning 200 tons of sucralose waste liquid per day, 1713.615 kg of hydrogen chloride is generated per hour, 798.122 kg of ammonia gas is consumed to generate ammonium chloride, the reaction heat is calculated as 300 kJ / mol, the heat released by the reaction of hydrogen chloride and ammonia gas per hour is 1713.615*1000 / 36.5*300 = 14084507.042 kJ, the specific heat of nitrogen is 1.038 kJ / (kg*℃), and the estimated specific heat of the flue gas is increased to 1.10 kJ / (kg*℃), so the temperature rise of the flue gas caused by the reaction heat of hydrogen chloride and ammonia gas is 14084507.042 / 1.10 / 173846.737 = 74.078 DEG C.

[0030] As can be seen, the reaction heat of hydrogen chloride and ammonia gas is considerable, and the heat will cause the temperature of the flue gas to rise significantly, providing the necessary conditions for steam generation.

[0031] Another technical solution of the application is a device for solving the problem of excessive production of hydrochloric acid in the treatment process of sucralose waste liquid, characterized in that it comprises a gas-gas reactor, a heat exchanger, a trap, a falling film condenser and a packed absorber connected in sequence, the wall of the gas-gas reactor is provided with a flue gas inlet and a liquid ammonia inlet, the flue gas inlet and the liquid ammonia inlet are arranged in the tangent direction of the wall of the gas-gas reactor, and the tangent directions of the flue gas inlet and the liquid ammonia inlet are opposite, the steam outlet in the shell side of the heat exchanger is connected to a steam drum for supplying the workshop, the bottom of the falling film condenser is provided with a condensed water outlet, the condensed water outlet is connected to a first circulating pump group, the outlet pipeline of the first circulating pump group is divided into three parts: one part returns to the top of the falling film condenser, another part enters the top of the trap, and the third part enters sewage treatment, the top of the packed absorber is provided with a washing water inlet, the washing water inlet is connected to a tap water pipeline, the bottom of the packed absorber is provided with a liquid outlet, the liquid outlet is connected to a second circulating pump group, and the outlet pipeline of the second circulating pump group is divided into two parts: one part returns to the top of the packed absorber, and the other part enters sewage treatment.

[0032] Further, the top of the gas-gas reactor is provided with a screen.

[0033] Further, the collector is provided with a spiral scraper agitator, which can scrape the wall-adhered ammonium chloride and water paste to the bottom of the collector, and the collector is externally provided with a cooling jacket.

[0034] The device and method disclosed by the application can solve the problem of excessive production of hydrochloric acid in the treatment process of sucralose waste liquid, and belong to the field of harmless treatment of chemical waste liquid.

[0035] The process of the application is simple and feasible, and effectively solves the problem of excessive production of hydrochloric acid in the treatment process of sucralose waste liquid.

[0036] The application ingeniously utilizes the reaction heat of hydrogen chloride and ammonia to generate steam for supplying to the workshop.

[0037] The collector in the application solves the problem of difficult recovery of ammonium chloride caused by ammonium chloride aerosol.

[0038] The filler absorber in the application uses water instead of liquid alkali to purify the flue gas, thereby reducing the pollution treatment cost. BRIEF DESCRIPTION OF DRAWINGS

[0039] Figure 1 It is a device structure schematic diagram of the application.

[0040] Figure 2 It is an analysis data screenshot when the tail gas reaches the on-line monitoring instrument.

[0041] In the figure: 1, gas-gas reactor; 2, heat exchanger; 3, collector; 4, falling film condenser; 5, filler absorber; 6, screen; 7, steam drum; 8, spiral scraper agitator; 9, cooling jacket; 10, first circulating pump group; 11, second circulating pump group. DETAILED DESCRIPTION

[0042] In order to make the purpose, technical scheme and advantages of the embodiments of the application more clear, the technical scheme in the embodiments of the application will be clearly and completely described below. If the specific conditions are not specified in the embodiments, the conventional conditions or the conditions recommended by the manufacturer are used. If the reagents or instruments used are not specified by the manufacturer, they are all conventional products that can be purchased on the market.

[0043] Example 1:

[0044] A method for solving the problem of excessive production of hydrochloric acid in the treatment process of sucralose waste liquid, comprising the following steps:

[0045] (1) Gas-gas reaction: the 201 DEG C flue gas after incineration and denitration of sucralose waste liquid enters the gas-gas reactor 1 through the flue gas inlet tangent, and liquid ammonia enters the gas-gas reactor 1 through the liquid ammonia inlet tangent, the liquid ammonia is heated into ammonia gas after entering the gas-gas reactor 1, the flue gas and the ammonia gas make spiral motion inside the gas-gas reactor 1 and rotate in opposite directions, the hydrogen chloride in the flue gas reacts with the ammonia gas to generate ammonium chloride particles, the reaction heat of the hydrogen chloride and the ammonia gas makes the flue gas temperature rise, the ammonium chloride particles are dispersed in the flue gas in the form of aerosol, the flue gas rises and is filtered through the screen 6 and then enters the heat exchanger 2 tube, the ammonium chloride aerosol enters the heat exchanger 2 tube with the flue gas, the large-particle ammonium chloride is filtered and settled to the bottom of the gas-gas reactor 1 and is discharged for drying treatment to obtain the ammonium chloride byproduct;

[0046] (2) Flue gas heat exchange: the 253 DEG C flue gas enters the heat exchanger 2 tube, the softened water in the heat exchanger 2 shell is heated by the flue gas to form steam, the pressure of the steam is 0.32 MPa, and the temperature is 136 DEG C, the steam enters the steam drum 7 and is used in the production workshop, the flue gas temperature is reduced to 142 DEG C after heat exchange in the heat exchanger 2 tube and enters the collector 3;

[0047] (3) Ammonium chloride trapping: the flue gas is cooled and sprayed in the collector 3, the ammonium chloride aerosol in the flue gas is absorbed and settled to the bottom of the collector 3 by the water mist, the spiral scraper agitator 8 in the collector 3 scrapes the ammonium chloride and water paste adhering to the wall to the bottom of the collector 3, the ammonium chloride slurry at the bottom of the collector 3 is discharged for drying treatment to obtain the ammonium chloride byproduct, the 103 DEG C flue gas after cooling and removal of the ammonium chloride aerosol is discharged through the flue gas outlet of the collector 3 and enters the falling film condenser 4;

[0048] (4) Falling film condensation: the flue gas is cooled to 48 DEG C in the falling film condenser 4, the gaseous water in the flue gas is condensed into liquid water, the condensed flue gas enters the packed absorber 5, the liquid water is discharged from the condensate water outlet of the falling film condenser 4, enters the first circulating pump set 10, and is divided into three parts by the first circulating pump set 10, one part is returned to the top of the falling film condenser 4, the second part is sprayed into the top of the collector 3 to trap the ammonium chloride particles in the flue gas into the water and settle to the bottom of the collector 3, and the third part enters the sewage treatment pipeline;

[0049] (5) Flue gas purification: the flue gas entering the packed absorber 5 is absorbed by water circulation to reach the environmental protection emission standard and is discharged to the atmosphere. The material liquid at the bottom of the packed absorber 5 enters the second circulating pump set 11 through the material liquid outlet, and is divided into two parts by the second circulating pump set 11, one part is returned to the top of the packed absorber 5, and the other part enters the sewage treatment pipeline.

[0050] Final emission of flue gas, concentration of nitrogen oxides (NOx) reduced to 100 mg / m 3 SO2 concentration reduced to 50 mg / m 3 Dust concentration reduced to 10 mg / m 3 HCl concentration reduced to 60 mg / m 3 Dioxin concentration reduced to 0.5 ng TEQ / m 3 The above pollutant emission limits are values at standard state, dry basis, and 11% reference oxygen.

[0051] Examples 2-8:

[0052] A method for solving the problem of excessive production of hydrochloric acid in the process of trichlorosucrose waste liquid treatment, the same as the steps of Example 1, the data of each stage are recorded as shown in Table 2.

[0053] Table 2 Parameter settings of Examples 1-8

[0054]

[0055] Note: The larger the amount of trichlorosucrose waste liquid incinerated, the greater the amount of hydrogen chloride produced, the greater the amount of ammonia gas required, and the more heat generated by the reaction between hydrogen chloride and ammonia gas. After the gas-gas reaction, the temperature of the flue gas will be higher.

[0056] Example 9:

[0057] As shown in Figure 1 A device for solving the problem of excessive production of hydrochloric acid in the process of trichlorosucrose waste liquid treatment, comprising a gas-gas reactor 1, a heat exchanger 2, a collector 3, a falling film condenser 4, and a packed absorber 5 connected in sequence. The gas-gas reactor 1 wall is provided with a flue gas inlet and a liquid ammonia inlet, both of which are arranged in the tangential direction of the gas-gas reactor wall 1, and the tangential directions of the flue gas inlet and the liquid ammonia inlet are opposite. The gas-gas reactor 1 is provided with a screen 6 at the top.

[0058] The steam outlet in the shell side of the heat exchanger 2 is connected to a steam drum 7 for use in the workshop. The collector 3 is provided with a spiral scraper agitator 8 inside, which can scrape the wall-sticking ammonium chloride and water paste to the bottom of the collector 3. The collector 3 is provided with a cooling jacket 9 outside. The falling film condenser 4 is provided with a condensate outlet at the bottom, which is connected to a first circulating pump set 10. The outlet pipeline of the first circulating pump set 10 is divided into three parts: one part returns to the top of the falling film condenser 4; another part enters the top of the collector 3 for spraying, capturing the ammonium chloride particles in aerosol state in the flue gas into water and settling to the bottom of the collector 3; the third part goes to sewage treatment.

[0059] The top of the filler absorber 5 is provided with a washing water inlet connected with a tap water pipeline, and the bottom of the filler absorber 5 is provided with a liquid outlet connected with a second circulating pump group 11, and the outlet pipeline of the second circulating pump group 11 is divided into two parts: one part returns to the top of the filler absorber 5, and the other part goes to sewage treatment. The first circulating pump group 10 and the second circulating pump group 11 are both composed of two parallel circulating pumps.

[0060] In the description of the present application, it should be understood that the terms indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the drawings, which is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application.

Claims

1. A method for solving the problem of excessive hydrochloric acid production during the treatment of sucralose waste liquid, characterized in that, Includes the following steps: (1) Gas-gas reaction: The denitrified flue gas and liquid ammonia enter the gas-gas reactor respectively. The hydrogen chloride in the flue gas reacts with the ammonia to generate ammonium chloride particles. The ammonium chloride particles disperse in the flue gas in an aerosol state. The flue gas rises and enters the heat exchanger tube side after being filtered by the screen. The ammonium chloride aerosol enters the heat exchanger tube side with the flue gas. Large ammonium chloride particles are filtered and settled to the bottom of the gas-gas reactor and discharged for recycling. (2) Flue gas heat exchange: The softened water in the shell side of the heat exchanger is heated by the flue gas to form steam, which enters the steam drum. After the flue gas is heated by the tube side of the heat exchanger, it enters the collector. The temperature of the flue gas after the heat exchange by the tube side of the heat exchanger is 140-170℃. (3) Ammonium chloride collection: The flue gas is cooled and sprayed in the collector. The ammonium chloride aerosol in the flue gas is absorbed by the water mist and settles to the bottom of the collector to form ammonium chloride slurry, which is discharged for recycling. The flue gas that has been cooled and removed of ammonium chloride aerosol is discharged through the flue gas outlet of the collector and enters the falling film condenser. The temperature of the flue gas discharged from the flue gas outlet of the collector is 100-120℃. (4) Falling film condensation: The flue gas is cooled down in the falling film condenser, and the gaseous water in the flue gas is condensed into liquid water. The condensed flue gas then enters the packing absorber. (5) Flue gas purification: The flue gas entering the packing absorber is absorbed by water circulation to meet the environmental emission standards and is then discharged into the atmosphere.

2. The method for solving the problem of excessive hydrochloric acid production during the treatment of sucralose waste liquid according to claim 1, characterized in that: In step (1), the flue gas and liquid ammonia enter the gas-gas reactor tangentially. After entering the gas-gas reactor, the liquid ammonia is heated to become ammonia gas. The flue gas and ammonia gas move in a spiral motion inside the gas-gas reactor and rotate in opposite directions.

3. The method for solving the problem of excessive hydrochloric acid production during the treatment of sucralose waste liquid according to claim 1, characterized in that: The temperature of the flue gas after denitrification in step (1) is 180-250℃. After the reaction, the temperature of the flue gas rises to 250-300℃ and enters the tube side of the heat exchanger.

4. The method for solving the problem of excessive hydrochloric acid production during the treatment of sucralose waste liquid according to claim 1, characterized in that: The steam pressure in step (2) is 0.3-0.6 MPa and the temperature is 133-159℃.

5. A device for solving the problem of excessive hydrochloric acid production during the treatment of sucralose waste liquid, characterized in that: The system includes a gas-to-gas reactor, a heat exchanger, a collector, a falling film condenser, and a packed absorber connected in sequence. The gas-to-gas reactor has a flue gas inlet and a liquid ammonia inlet on its wall. Both the flue gas inlet and the liquid ammonia inlet are located tangentially to the gas-to-gas reactor wall, and their tangential directions are opposite. The steam outlet in the shell side of the heat exchanger is connected to a steam drum. The bottom of the falling film condenser has a condensate outlet, which is connected to a first circulating pump group. The outlet pipeline of the first circulating pump group is divided into three parts: one part returns to the top of the falling film condenser, another part enters the top of the collector, and the third part enters the wastewater treatment system. The packing absorber is provided with a washing water inlet at the top and a liquid outlet at the bottom. The liquid outlet is connected to a second circulation pump set. The outlet pipeline of the second circulation pump set is divided into two parts: one part returns to the top of the packing absorber, and the other part enters the sewage treatment.

6. The apparatus for solving the problem of excessive hydrochloric acid production during the treatment of sucralose waste liquid according to claim 5, characterized in that: The gas reactor is equipped with a screen at the top.

7. The apparatus for solving the problem of excessive hydrochloric acid production during the treatment of sucralose waste liquid according to claim 5, characterized in that: The trap is equipped with a spiral scraper agitator inside, and a cooling jacket is provided outside the trap.

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