Process for recovering sodium formate in sodium hydrosulfite

Abstract

The invention provides a recovery process of sodium formate in sodium hydrosulfite, and relates to the field, the recovery process comprises the following steps: 1, carrying out evaporation concentration on a sodium hydrosulfite filtrate to prepare a saturated solution; 2, the saturated solution is subjected to evaporative crystallization, and crystals are prepared; step 3, pressing the crystal into a drying kettle for further filter pressing to prepare solid sodium formate; and 4, adding water to dissolve solid sodium formate, and pumping the sodium formate solution into the preparation kettle to circularly enter a sodium hydrosulfite preparation process. After the method is implemented, the sodium formate recovery cost is reduced, the three rectification evaporation kettles and the screw vacuum pump can be stopped, and the method is simple in process operation, and can effectively reduce the recovery energy consumption, improve the field environment and reduce the generation of tail gas.

Description

Technical Field

[0001] The invention relates to the technical field of sodium formate recovery, and in particular to a process for recovering sodium formate from sodium hydrosulfite. Background Art

[0002] Sodium formate is one of the main raw materials for producing sodium formate. In the production process, the sodium formate filtrate contains a large amount of sodium formate. In order to improve the utilization rate of sodium formate, in the production process of sodium formate, the existing sodium formate filtrate is usually evaporated and concentrated by the first and second effect evaporators, and then further evaporated and crystallized by the curing kettle, extracted with methanol, and then pressed into the drying kettle. After filter pressing, methanol washing, filter pressing, drying or centrifugation, solid sodium formate is obtained. The solid sodium formate is then manually discharged and packaged and transported to the sodium formate preparation kettle by forklift to prepare sodium formate suspension, which is then used for the synthesis of sodium formate.

[0003] The above process has many operating steps and complicated procedures. In addition, packaging, transportation and unloading increase the workload and increase the production labor cost. The methanol distillation and evaporation process increases steam consumption, and the centrifugation or drying process increases power consumption. In the sodium formate recovery process, methanol washing is required to remove impurities in the recovered sodium formate. The amount of methanol used is large. In order to recover this part of methanol, distillation and evaporation are required. While consuming steam, a certain amount of tail gas containing a small amount of methanol will be produced, which needs to be treated to meet the standards before being discharged. Summary of the invention

[0004] 1. Technical issues to be resolved

[0005] In view of the deficiencies of the prior art, the present invention provides a process for recovering sodium formate from sodium hydrosulfite, which solves the technical problems of the prior sodium formate recovery process being complex, high energy consumption and high production cost.

[0006] (II) Technical solution

[0007] To achieve the above objectives, the present invention is implemented through the following technical solutions:

[0008] The recovery process of sodium formate in hydrosulfite comprises the following steps:

[0009] Step 1, evaporating and concentrating the sodium hypochlorite filtrate to obtain a saturated solution;

[0010] Step 2, evaporating and crystallizing the saturated solution to obtain crystals;

[0011] Step 3, pressing the crystals into a drying kettle for further filtering to obtain solid sodium formate;

[0012] Step 4: Add water to dissolve solid sodium formate, and pump the sodium formate solution into the preparation kettle to circulate into the hydrosulfite preparation process.

[0013] Preferably, the specific method of evaporation and concentration in step 1 is: the hydrosulfite filtrate is sequentially passed through a first-effect evaporator and a second-effect evaporator for evaporation and concentration.

[0014] Preferably, in step 1, the relevant parameters for the hydrosulfite filtrate to be evaporated and concentrated by a first-effect evaporator are: an operating temperature of 110 to 140° C. and an operating pressure of 0.15 to 0.25 MPa.

[0015] Preferably, in step 1, the relevant parameters when the hydrosulfite filtrate is evaporated and concentrated by a second-effect evaporator are: operating temperature 100 to 120° C., operating pressure -0.1 to -0.04 MPa.

[0016] Preferably, the specific method of evaporation and crystallization in step 2 is: pumping the saturated solution into a curing kettle, evaporating and crystallizing in the curing kettle, with an operating temperature of 100 to 120° C. and an operating pressure of -0.1 to -0.04 MPa, and observing through the sight glass on the curing kettle that the material in the kettle is viscous.

[0017] Preferably, the relevant parameters for the filter pressing of the crystals in the drying kettle in step 3 are: pressure of 0.3-0.35 MPa, temperature of 90-120° C., and filter pressing time of 1.5 h.

[0018] Preferably, the temperature of water added in step 4 is 85-95°C, and the amount added is 0.8-1.0 m 3 The concentration of the prepared sodium formate solution is 60% to 75%.

[0019] (III) Beneficial effects

[0020] The present invention provides a process for recovering sodium formate from sodium hydrosulfite. Compared with the prior art, the present invention has the following beneficial effects:

[0021] 1. After the implementation of the present invention, the cost of recovering sodium formate is reduced. At present, the packaging fee of sodium formate is 28 yuan / ton, and the unloading fee of sodium formate is 22 yuan / ton, which can reduce the labor cost by 240,000 yuan throughout the year.

[0022] 2. The improved process of the present invention can stop using three distillation evaporators and screw vacuum pumps, which can reduce the opening time by 15 hours per day and reduce the power electricity cost throughout the year: 15×330×(7.5+18.5-11)×0.6=45,000 yuan;

[0023] 3. The present invention is simple in process operation, can effectively reduce recovery energy consumption, improve the on-site environment, and reduce tail gas generation. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0025] Figure 1 is a process flow chart of an embodiment of the present invention;

[0026] Figure 2 is a flow chart of a device according to an embodiment of the present invention;

[0027] Among them, 1. residual liquid tank; 2. residual liquid pump; 3. first-effect evaporator; 4. second-effect evaporator; 5. curing kettle; 6. drying kettle; 7. evaporating kettle; 8. conveying pump; 9. preparation kettle. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are clearly and completely described. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] The embodiment of the present application provides a process for recovering sodium formate in sodium hydrosulfite, thereby solving the technical problems of complex, high energy consumption and high production cost of the existing sodium formate recovery process, reducing the sodium formate recovery cost, reducing recovery energy consumption, improving the on-site environment and reducing tail gas generation.

[0030] In order to better understand the above technical solution, the above technical solution will be described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0031] Embodiment 1:

[0032] like Figure 1 , Figure 2 As shown, the recovery process of sodium formate in hydrosulfite specifically comprises the following steps:

[0033] Step 1, the sodium hypochlorite filtrate is pumped from the residual liquid tank 1 to the first-effect evaporator 3 and the second-effect evaporator 4 in sequence through the residual liquid pump 2 for evaporation and concentration to obtain a saturated solution;

[0034] When the filtrate of the hydrosulfite is evaporated and concentrated by the first-effect evaporator 3, the operating temperature is 110°C and the operating pressure is 0.15MPa. When the filtrate of the hydrosulfite is evaporated and concentrated by the second-effect evaporator 4, the operating temperature is 100°C and the operating pressure is -0.1MPa.

[0035] Step 2, pump the saturated solution into the curing kettle 5, evaporate and crystallize in the curing kettle 5, the operating temperature is 100°C, the operating pressure is -0.1MPa, and the material in the kettle can be observed to be viscous through the upper mirror of the curing kettle 5, and the crystals are obtained;

[0036] Step 3, the crystals are pressed into a drying kettle 6 for further filtration, the pressure in the drying kettle 6 is 0.3 MPa, the temperature is 90° C., and the filtration time is 1.5 h to obtain solid sodium formate;

[0037] Step 4: Use temperature of 85°C and dosage of 0.8m 3 The solid sodium formate is dissolved in water to prepare a sodium formate solution with a concentration of 60%, and the sodium formate solution is sent to the preparation kettle 8 through the delivery pump 7 and circulated into the sodium hydrosulfite preparation process.

[0038] Embodiment 2:

[0039] like Figure 1 , Figure 2 As shown, the recovery process of sodium formate in hydrosulfite specifically comprises the following steps:

[0040] Step 1, the sodium hypochlorite filtrate is pumped from the residual liquid tank 1 to the first-effect evaporator 3 and the second-effect evaporator 4 in sequence through the residual liquid pump 2 for evaporation and concentration to obtain a saturated solution;

[0041] When the filtrate of the sodium hypochlorite is evaporated and concentrated by the first-effect evaporator 3, the operating temperature is 140°C and the operating pressure is 0.25MPa. When the filtrate of the sodium hypochlorite is evaporated and concentrated by the second-effect evaporator 4, the operating temperature is 120°C and the operating pressure is -0.04MPa.

[0042] Step 2, pump the saturated solution into the curing kettle 5, evaporate and crystallize in the curing kettle 5, the operating temperature is 120°C, the operating pressure is -0.04MPa, and the material in the curing kettle 5 can be observed to be viscous through the mirror on the curing kettle 5, and the crystals are obtained;

[0043] Step 3, the crystals are pressed into a drying kettle 6 for further filtration, the pressure in the drying kettle 6 is 0.35 MPa, the temperature is 120° C., and the filtration time is 1.5 h to obtain solid sodium formate;

[0044] Step 4: Use temperature at 95°C and dosage at 1.0m 3 Solid sodium formate is dissolved in water to prepare a sodium formate solution with a concentration of 75%, and the sodium formate solution is sent to the preparation kettle 8 through the delivery pump 7 and circulated into the sodium hydrosulfite preparation process.

[0045] In summary, compared with the prior art, the present invention has the following beneficial effects:

[0046] 1. After the implementation of the present invention, the cost of recovering sodium formate is reduced. At present, the packaging fee of sodium formate is 28 yuan / ton, and the unloading fee of sodium formate is 22 yuan / ton, which can reduce the labor cost by 240,000 yuan throughout the year.

[0047] 2. The improved process of the present invention can stop using three distillation evaporators and screw vacuum pumps, which can reduce the opening time by 15 hours per day and reduce the power electricity cost throughout the year: 15×330×(7.5+18.5-11)×0.6=45,000 yuan;

[0048] 3. The present invention is simple in process operation, can effectively reduce recovery energy consumption, improve the on-site environment, and reduce tail gas generation.

[0049] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0050] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A process for recovering sodium formate from hydrosulfite, characterized in that: The following steps are involved: Step 1, evaporating and concentrating the sodium hypochlorite filtrate to obtain a saturated solution; Step 2, evaporating and crystallizing the saturated solution to obtain crystals; Step 3, pressing the crystals into a drying kettle for further filtering to obtain solid sodium formate; Step 4: Add water to dissolve solid sodium formate, and pump the sodium formate solution into the preparation kettle to circulate into the hydrosulfite preparation process.

2. The process for recovering sodium formate from hydrosulfite according to claim 1, wherein: The specific method of evaporation and concentration in step 1 is: the hydrosulfite filtrate is sequentially passed through a first-effect evaporator and a second-effect evaporator for evaporation and concentration.

3. The process for recovering sodium formate from hydrosulfite as claimed in claim 2, characterized in that: In step 1, the relevant parameters for the hydrosulfite filtrate to be evaporated and concentrated by a first-effect evaporator are: operating temperature 110-140° C., operating pressure 0.15-0.25 MPa.

4. The process for recovering sodium formate from hydrosulfite according to claim 2, characterized in that: The relevant parameters when the hydrosulfite filtrate in step 1 is evaporated and concentrated by the second-effect evaporator are: operating temperature 100-120° C., operating pressure -0.1-0.04 MPa.

5. The process for recovering sodium formate from hydrosulfite according to claim 1, wherein: The specific method of evaporation and crystallization in step 2 is: pumping the saturated solution into a curing kettle, evaporating and crystallizing in the curing kettle, the operating temperature is 100 to 120° C., the operating pressure is -0.1 to -0.04 MPa, and the material in the curing kettle can be observed to be viscous through the sight glass on the curing kettle.

6. The process for recovering sodium formate from hydrosulfite according to claim 1, characterized in that: The relevant parameters for the filter pressing of the crystals in the drying kettle in step 3 are: pressure of 0.3-0.35 MPa, temperature of 90-120° C., and filter pressing time of 1.5 h.

7. The process for recovering sodium formate from hydrosulfite according to claim 1, characterized in that: The temperature of water added in step 4 is 85-95°C and the amount added is 0.8-1.0 m 3 The concentration of the prepared sodium formate solution is 60% to 75%.

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