A system and method for continuous production of neutralizing liquid and adjustment of nitrous ratio

Abstract

The application discloses a system and method for continuously extracting neutralizing liquid and adjusting nitrous ratio, which comprises a first alkali absorption unit, secondary alkali liquid from a dissolving alkali process and NOx gas from an ammonia oxidation process are sent to the first alkali absorption unit to carry out reverse reaction absorption to prepare pre-neutralizing liquid; the pre-neutralizing liquid prepared by the first alkali absorption unit and the NOx gas from the ammonia oxidation process carry out reverse reaction absorption in a tuning unit to prepare neutralizing liquid, and the tuning unit comprises a first tuning unit and a second tuning unit; the pre-neutralizing liquid and the NOx gas from the ammonia oxidation process carry out reverse reaction absorption in the first tuning unit to reduce the alkalinity of the pre-neutralizing liquid; the second tuning unit is in communication with the first tuning unit, the pre-neutralizing liquid and the NOx gas after reaction in the first tuning unit carry out further reaction absorption to further reduce the alkalinity of the pre-neutralizing liquid, and finally the neutralizing liquid is obtained and continuously extracted. x The application has great significance in continuously and stably producing, improving product quality, reducing labor intensity of workers, reducing labor cost and saving fixed asset investment and the like. x The application has great significance in continuously and stably producing, improving product quality, reducing labor intensity of workers, reducing labor cost and saving fixed asset investment and the like.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of two-sodium nitrate production device, and relates to a system for continuously taking out neutralizing liquid and adjusting nitrite ratio, and also relates to a working method of the system. BACKGROUND

[0002] In the two-sodium nitrate production process, the alkali absorption process is to make NO x react and absorb in the tower with primary alkali or secondary alkali, mainly generating lean liquid and neutralizing liquid, i.e. a process in which the aqueous solution mainly composed of sodium nitrite and sodium nitrate is generated, then the lean liquid is sent to the alkali dissolving process to be mixed with sodium carbonate to prepare secondary alkali, and the neutralizing liquid is sent to the sodium nitrite evaporation process to be evaporated, crystallized, centrifuged and dried to produce sodium nitrite products.

[0003] In the alkali absorption process, NO x mainly reacts with sodium carbonate to generate sodium nitrite and sodium nitrate, and the total reaction formula is as follows:

[0004] 2NO2+Na2CO3=NaNO2+NaNO3+CO2

[0005] NO+NO2+Na2CO3=2NaNO2+CO2

[0006] At present, the neutralizing liquid discharge tower in the two-sodium production process adopts intermittent discharge, and the main mode of the usual production operation is as follows: when the circulating liquid of the neutralizing liquid discharge tower approaches the end point, the alkalinity in the circulating liquid (neutralizing liquid) is analyzed, when the alkalinity reaches 2-5 g / L, it indicates that the absorption has reached the end point, the neutralizing liquid is sent to the neutralizing liquid tank, and the taking out is stopped when the liquid level of the neutralizing liquid discharge tower decreases to the set value, then the lean liquid is supplemented to the neutralizing liquid discharge tower, and when the liquid level is normal, the neutralizing liquid discharge tower resumes normal operation. The disadvantages of the above-mentioned alkali absorption tower operation mode are: 1) the alkalinity of the neutralizing liquid is always fluctuating, and even the neutralizing liquid may be acidic, which is affected by the time and frequency of manual analysis of the alkalinity of the neutralizing liquid; 2) due to the intermittent operation of the taking out and liquid supplementing of the neutralizing liquid discharge tower, the operation of the alkali absorption process fluctuates greatly. Therefore, improving the content of sodium nitrite in the neutralizing liquid and realizing the continuous discharge of the neutralizing liquid have become a difficult problem to be solved in the two-sodium nitrate production process. SUMMARY

[0007] The purpose of the present application is to provide a system for continuously taking out neutralizing liquid and adjusting nitrite ratio, which overcomes the disadvantages of the existing alkali absorption tower operation mode.

[0008] The present application also provides a method for continuously taking out neutralizing liquid and adjusting nitrite ratio, which also overcomes the disadvantages of the existing alkali absorption tower operation mode.

[0009] The first technical solution adopted by the present application is a system for continuously taking out neutralizing liquid and adjusting nitrite ratio, which comprises:

[0010] The first alkali absorption unit, the secondary alkali solution from the alkali dissolution process and the NOx gas from the ammonia oxidation process are sent to the first alkali absorption unit for reverse reaction absorption to produce a pre-neutralized solution;

[0011] The tuning unit includes a first tuning unit and a second tuning unit;

[0012] In the first tuning unit, the pre-neutralization liquid and the NOx gas from the ammonia oxidation process undergo a reverse reaction absorption in the first tuning unit to reduce the alkalinity of the pre-neutralization liquid;

[0013] The second tuning unit is connected to the first tuning unit. The pre-neutralized liquid reacts with the NOx in the first tuning unit and further absorbs it, further reducing the alkalinity of the pre-neutralized liquid. Finally, the neutralized liquid is obtained and continuously extracted to the sodium sulfate evaporation process.

[0014] The second alkali absorption unit, the gas phase after the reaction of the second tuning unit is combined with the gas phase after the reaction of the first alkali absorption unit and sent to the second alkali absorption unit for alkali liquid absorption reaction to reduce the NOx content in the exhaust gas.

[0015] Another technical solution adopted by the present invention is a method for continuously producing neutralized liquid and adjusting the nitrous ratio. The method uses the above-mentioned system for continuously producing neutralized liquid and adjusting the nitrous ratio, comprising the following steps:

[0016] Step 1: NO from the ammonia oxidation process x Passed into the first tuning unit;

[0017] Step 2: The pre-neutralized liquid from the first alkali absorption unit is sent to the first tuning unit to x Perform reaction absorption;

[0018] Step 3: The pre-neutralized liquid after the reaction in the first tuning unit is sent to the second tuning unit. The pre-neutralized liquid is reacted with the NO obtained in step 1. x Further reaction absorption, the neutralized liquid after the reaction is continuously sent to the sodium sulfite evaporation process, the NO x The gas is combined with the gas phase of the first alkali absorption unit and then sent to the second alkali absorption unit.

[0019] The present invention is also characterized in that:

[0020] The first tuning unit generates pre-neutralization liquid to absorb NO x The rate is greater than the oxidation rate of NO.

[0021] The second adjusting unit comprises several series adjusting units, the pre-neutralized liquid sequentially passes through the several series adjusting units, each series adjusting unit is in communication with the first adjusting unit, the NOx in the pre-neutralized liquid reacts with the first adjusting unit in the series adjusting unit x Absorption by step-by-step reaction.

[0022] The alkalinity of the pre-neutralized liquid sent to the first adjusting unit from the first alkali absorption unit is 20-50 g / L.

[0023] The alkalinity of the pre-neutralized liquid after the reaction of step 2 in the first adjusting unit is 10-15 g / L.

[0024] The alkalinity of the pre-neutralized liquid after the reaction of step 3 in the second adjusting unit is 2-5 g / L.

[0025] The operating conditions of the first alkali absorption unit and the adjusting unit are as follows: the operating temperature is 80-100 ℃, and the operating pressure is 40-60 KPa.

[0026] The beneficial effects of the present application are as follows:

[0027] 1. The present application can realize continuous extraction of the neutralized liquid and adjustment of the sodium nitrite content in the neutralized liquid.

[0028] 2. The present application has great significance in continuous and stable production, improvement of product quality, reduction of labor intensity, reduction of labor cost and saving of fixed asset investment. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 is a module diagram of the system for continuously extracting the neutralized liquid and adjusting the nitrite ratio according to the present application;

[0030] Figure 2 is a structure diagram of the system for continuously extracting the neutralized liquid and adjusting the nitrite ratio according to the present application;

[0031] Figure 3 is a structure diagram of the adjusting tower of the system for continuously extracting the neutralized liquid and adjusting the nitrite ratio according to the present application;

[0032] In the figure, 1 is a tower body, 2 is a liquid outlet, 3 is a gas inlet, 4 is a first filler, 5 is a pre-neutralized liquid circulation inlet, 6 is a first filler pressing ring, 7 is a first filler supporting ring, 8 is a partition plate, 9 is a lotus nozzle distributor, 10 is a gas phase outlet, 11 is a second filler, 12 is a gas lifting cap, 13 is a neutralized liquid outlet pipe, 14 is a gas outlet, 15 is an adjusting tower, and 16 is a 1# alkali absorption tower. DETAILED DESCRIPTION

[0033] The present application will be described in detail below in combination with the drawings and specific embodiments.

[0034] The first technical solution adopted by the present application is, as shown in Figure 1 A system for continuously collecting neutralizing liquid and adjusting nitrous ratio, comprising:

[0035] A first alkali absorption unit, secondary alkali liquid from a dissolving alkali process and NOx gas from an ammonia oxidation process are sent to the first alkali absorption unit for reverse reaction absorption to prepare pre-neutralizing liquid;

[0036] A tuning unit, the tuning unit comprises a first tuning unit and a second tuning unit;

[0037] The first tuning unit, the pre-neutralizing liquid and the NOx gas from the ammonia oxidation process are subjected to reverse reaction absorption in the first tuning unit to reduce the alkalinity of the pre-neutralizing liquid;

[0038] The second tuning unit, in communication with the first tuning unit, the pre-neutralizing liquid and the NOx after reaction in the first tuning unit are further subjected to reaction absorption to further reduce the alkalinity of the pre-neutralizing liquid, and finally obtain neutralizing liquid and continuously collect to a sodium sulfite evaporation process;

[0039] The second alkali absorption unit, the gas phase after reaction in the second tuning unit and the gas phase after reaction in the first alkali absorption unit are combined and sent to the second alkali absorption unit for alkali absorption reaction to reduce the content of NOx in the tail gas.

[0040] Another technical solution adopted by the present application is a method for continuously collecting neutralizing liquid and adjusting nitrous ratio, a method for continuously collecting neutralizing liquid and adjusting nitrous ratio, using the above-mentioned system for continuously collecting neutralizing liquid and adjusting nitrous ratio, comprising the following steps:

[0041] Step 1, NO x from an ammonia oxidation process is introduced into the first tuning unit;

[0042] Step 2, pre-neutralizing liquid from the first alkali absorption unit is sent to the first tuning unit for reaction absorption of NO x ;

[0043] Step 3, the pre-neutralizing liquid after reaction in the first tuning unit is sent to the second tuning unit, the pre-neutralizing liquid and the NO x obtained in step 1 are further subjected to reaction absorption, the neutralizing liquid after reaction is continuously sent to a sodium sulfite evaporation process, and the NO x gas after reaction and the gas phase from the first alkali absorption unit are combined and sent to the second alkali absorption unit.

[0044] The first tuning unit absorbs NO x at a speed greater than the oxidation speed of NO.

[0045] The second tuning unit comprises a plurality of series tuning units in series, and the pre-neutralized liquid sequentially passes through the plurality of series tuning units in series. Each series tuning unit is in communication with the first tuning unit, and the NOx in the pre-neutralized liquid reacts with the first tuning unit in the series tuning unit x Absorption by step-by-step reaction.

[0046] The alkalinity of the pre-neutralized liquid sent to the first tuning unit from the first alkali absorption unit is 20-50 g / L.

[0047] The alkalinity of the pre-neutralized liquid after the reaction of step 2 in the first tuning unit is 10-15 g / L.

[0048] The alkalinity of the pre-neutralized liquid after the reaction of step 3 in the second tuning unit is 2-5 g / L.

[0049] The operating conditions of the first alkali absorption unit and the tuning unit are as follows: the operating temperature is 80-100 ℃, and the operating pressure is 40-60 KPa.

[0050] Embodiment 1

[0051] In this example, there is a 1# alkali absorption tower as the first alkali absorption unit and a tuning tower as the tuning unit. The 1# alkali absorption tower is in communication with the tuning tower, the tuning tower is in communication with a 2# alkali absorption tower, and the 2# alkali absorption tower is the second alkali absorption unit.

[0052] The tuning tower comprises a tower body 1, as shown in Figure 2 , 3 The tower body 1 is divided into an upper tower body and a lower tower body. The upper tower body is the second tuning unit. The upper tower body and the lower tower body are connected and communicate. The bottom end of the lower tower body is provided with a liquid outlet 2. The outer wall of the lower tower body is provided with a gas inlet 3 and a pre-neutralized liquid circulation inlet 5. The position of the pre-neutralized liquid circulation inlet 5 is higher than that of the gas inlet 3. The inside of the lower tower body is provided with a first filler 4. The first filler 4 is located between the gas inlet 3 and the pre-neutralized liquid circulation inlet 5.

[0053] The top end of the first filler 4 is provided with a first filler pressing ring 6, and the bottom end is provided with a first filler supporting ring 7.

[0054] The inside of the upper tower body is provided with a broken tray. A plurality of partitions 8 are vertically fixed on the surface of the broken tray. The partitions 8 divide the upper tower body into a plurality of chambers, specifically a first chamber, a second chamber, a third chamber, etc. The first chamber, the second chamber, the third chamber, etc. are series tuning units in series. A lotus shower distributor 9 is arranged in each chamber. The top end of the chamber is provided with a gas phase outlet 10. A second filler 11 is arranged in the chamber. A gas lifting cap 12 is arranged on the upper surface of the broken tray. The gas inlet of the gas lifting cap 12 is arranged on the upper surface of the broken tray. The gas lifting cap 12 is arranged below the second filler 11.

[0055] The gas-lifting caps 12 are respectively arranged at the center of the bottom of each chamber.

[0056] The sum of the angles between the several partitions 8 is 360°.

[0057] The outer wall of the chamber is provided with a neutralizing liquid outlet pipe 13, the inlet end of which is communicated with the inside of the chamber, the inlet end is arranged outside the gas inlet of the gas-lifting cap 12, and the outlet end is arranged on the outer wall of the chamber, and the outlet end is connected with a third circulating pipe, which is used for communicating two adjacent chambers.

[0058] In the upper tower body, a partition tower structure is adopted, and in the circular tower body, N partitions are arranged to divide the upper tower body into N parallel fan-shaped tower bodies, and each fan-shaped tower body is an independent absorption tower. According to the need, corresponding liquid distributors, packing pressure rings, packings, packing support rings, gas-lifting caps, tower bottom liquid collecting tanks and other accessories can be arranged; the lower tower body is in gas phase series connection with the upper tower body, and the lower tower body is a single packing absorption tower, and according to the need, liquid distributors, packing pressure rings, packings and packing support rings and other absorption tower accessories can be arranged in the tower body.

[0059] The inlet end of the third circulating pipe is connected with the neutralizing liquid outlet pipe 13 of one chamber, and the outlet end is connected with the lotus-shaped nozzle distributor 9 of another adjacent chamber. The inlet end of one of the lotus-shaped nozzle distributors 9 is connected with the outlet end of the second circulating pipe, the inlet end of the second circulating pipe is connected with the outer wall of the first circulating pipe, and a valve and a circulating pump are arranged on the second circulating pipe.

[0060] The outer wall of the upper tower body is provided with a gas outlet 14, which is arranged below the broken tray, and the horizontal position of the gas outlet 14 and the gas inlet of the gas-lifting cap 12 is 100 mm.

[0061] Taking a 100,000 tons / year sodium nitrate and sodium nitrite production device as an example, the embodiment of the application is described.

[0062] The secondary alkali liquid from the alkali dissolving process is sent to the tower kettle of the 1# alkali absorption tower 16, and then is sent to the top of the 1# alkali absorption tower 16 through the 1# alkali absorption tower circulating pump, and is mixed with the NO x The gas is reversely reacted and absorbed in the tower, the temperature at the top of the 1# alkali absorption tower is controlled at 80-100℃, and the pressure is controlled at 40-60KPa, and finally the pre-neutralizing liquid is obtained, a total of 45285.5kg / h, of which 62% is water, 3% is sodium carbonate, 3% is sodium nitrate and 32% is sodium nitrite.

[0063] At this time, the pre-neutralization liquid alkali degree of 1#alkali absorption tower 16 reaches 36g / L, then 9057.1kg / h of pre-neutralization liquid is sent to the lean liquid tank to produce secondary alkali liquid; the remaining 36228.4kg / h of pre-neutralization liquid is sent to the lower tower body of the optimization tower 15, using the principle of "large liquid quantity and small gas quantity", the pre-neutralization liquid is sent to the middle part of the optimization tower 15 by the optimization tower circulating pump at a circulating amount of 550m 3 / h, and the NO x gas from the ammonia oxidation process is further absorbed by reverse reaction in the tower to further reduce the alkali degree of the pre-neutralization liquid.

[0064] At this time, the pre-neutralization liquid alkali degree reaches 13g / L, the regulating valve is opened to send the pre-neutralization liquid to the first chamber of the upper tower body of the optimization tower 15, and the NO x is further absorbed by reaction to further reduce the alkali degree of the pre-neutralization liquid.

[0065] When the liquid level of the first chamber of the upper tower body of the optimization tower 15 reaches 60%-80%, the pipeline pump is opened to send the pre-neutralization liquid reacted in the first chamber of the upper tower body of the optimization tower 15 to the second chamber of the upper tower body of the optimization tower 15, and the NO x is further absorbed by reaction to further reduce the alkali degree of the pre-neutralization liquid.

[0066] When the liquid level of the second chamber of the upper tower body of the optimization tower 15 reaches 60%-80%, the pipeline pump is opened to send the pre-neutralization liquid reacted in the second chamber of the upper tower body of the optimization tower 15 to the third chamber of the upper tower body of the optimization tower 15, and the NOx reacted in the lower tower body of the optimization tower 15 is further absorbed by reaction, and the alkali degree of the neutralization liquid after reaction reaches 3.5g / L, then the neutralization liquid is sent to the sodium sulfite evaporation process using the potential difference, at this time the flow rate of the neutralization liquid is 35601.7kg / h, of which 60.5% is water, 0.3% is sodium carbonate, 3.2% is sodium nitrate, 35.8% is sodium nitrite and 0.2% is sodium chloride. Then the neutralization liquid passes through the sodium sulfite evaporation process, the conversion process and the sodium nitrate evaporation process, and finally 9221.43kg / h of sodium nitrite product and 5921.375kg / h of sodium nitrate product are obtained.

Claims

1. A system for continuously extracting neutralized liquid and adjusting nitrite ratio, characterized in that: Includes: In the first alkali absorption unit, the secondary alkali liquid from the alkali dissolution process and the NO from the ammonia oxidation process x The gas is sent to the first alkali absorption unit for reverse reaction absorption to produce a pre-neutralized liquid; A tuning unit, wherein the pre-neutralized liquid produced in the first alkali absorption unit and the NOx gas from the ammonia oxidation process undergo a reverse reaction absorption in the tuning unit to produce a neutralized liquid, and the tuning unit includes a first tuning unit and a second tuning unit; In the first tuning unit, the pre-neutralized liquid and the NO from the ammonia oxidation process x The gas undergoes reverse reaction absorption in the first tuning unit to reduce the alkalinity of the pre-neutralization solution; The second tuning unit is connected to the first tuning unit, and the NO produced by the reaction of the pre-neutralization liquid and the first tuning unit x Further reaction and absorption further reduce the alkalinity of the pre-neutralized solution, and finally obtain the neutralized solution which is continuously withdrawn to the sodium sulfate evaporation process; The second alkali absorption unit, the gas phase after the reaction of the second tuning unit is combined with the gas phase after the reaction of the first alkali absorption unit and sent to the second alkali absorption unit for alkali absorption reaction to reduce the NOx content in the exhaust gas; The second tuning unit includes several cascade tuning units connected in series. The pre-neutralized liquid passes through several cascade tuning units in sequence. Each cascade tuning unit is connected to the first tuning unit. The pre-neutralized liquid reacts with the NO in the cascade tuning unit. x Step-by-step reaction absorption.

2. A system for continuously extracting neutralized liquid and adjusting nitrite ratio according to claim 1, characterized in that: The pre-neutralization liquid in the first tuning unit absorbs NO x The rate is greater than the oxidation rate of NO.

3. A method for continuously extracting neutralized liquid and adjusting the nitrite ratio, using the system for continuously extracting neutralized liquid and adjusting the nitrite ratio as claimed in claim 1, characterized in that: The following steps are involved: Step 1: NO from the ammonia oxidation process x Passed into the first tuning unit; Step 2: The pre-neutralized liquid from the first alkali absorption unit is sent to the first tuning unit to x Perform reaction absorption; Step 3: The pre-neutralized liquid after the reaction in the first tuning unit is sent to the second tuning unit. The pre-neutralized liquid is mixed with the NO obtained in step 1. x Further reaction absorption, the neutralized liquid after the reaction is continuously sent to the sodium sulfite evaporation process, the NO x The gas is combined with the gas phase of the first alkali absorption unit and then sent to the second alkali absorption unit.

4. The method for continuously extracting neutralized liquid and adjusting the nitrite ratio according to claim 3, wherein: The alkalinity of the pre-neutralization liquid sent from the first alkali absorption unit to the first tuning unit is 20-50 g / L.

5. The method for continuously extracting neutralized liquid and adjusting nitrite ratio according to claim 3, wherein: The alkalinity of the pre-neutralized solution after the reaction in step 2 in the first tuning unit is 10-15 g / L.

6. The method for continuously extracting neutralized liquid and adjusting nitrite ratio according to claim 3, characterized in that: The alkalinity of the pre-neutralized solution after the reaction in step 3 in the second tuning unit is 2 to 5 g / L.

7. The method for continuously extracting neutralized liquid and adjusting nitrite ratio according to claim 3, characterized in that: The operating conditions of the first alkali absorption unit and the tuning unit are an operating temperature of 80-100°C and an operating pressure of 40-60KPa.

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