CN114349629B - A system and process for recovering sodium acetate from oil by-products - Google Patents

Abstract

The present invention belongs to the field of refining technology for oil by-products, and specifically discloses a recovery and treatment system and process for sodium acetate in oil by-products, including a sodium acetate aqueous solution decolorization process, a sodium acetate aqueous solution filtration and pH adjustment process, and a sodium acetate aqueous solution evaporation process. Through the system and recovery process of the present invention, the oil, acidic substances, and oil phase in the crude sodium acetate aqueous solution are effectively removed, and the sodium acetate aqueous solution with a water content of 90% is evaporated to a water content of about 5% through a three effect evaporator, which saves about 70% of energy compared to a single effect evaporator.

Description

A system and process for recovering sodium acetate from oil by-products

Technical Field

The invention belongs to the technical field of oil by-product refining, and in particular relates to a system and process for recovering and treating sodium acetate in oil by-products.

Background Art

Soapstock is a by-product of the grain and oil processing industry. It is formed in the alkali refining and deacidification step of the oil refining section. In this process, sodium hydroxide is used to neutralize the free fatty acids (FFA) in the crude oil. The generated soap absorbs some other impurities and precipitates and separates from the oil to form soapstock. The main components of soapstock are as follows: sodium fatty acid, neutral oil, water and other impurities.

At present, there are innovative processes using organic acids to treat soap stock, such as acidification with acetic acid to obtain by-products such as crude sodium acetate, fatty acids, neutral oils, etc. Among them, sodium acetate is an indispensable chemical raw material in sewage treatment, food industry, detergent additives and health industry. If the sodium acetate aqueous solution is reasonably recycled and reused, there will be a great market demand.

Summary of the invention

The purpose of the present invention is to provide a system and process for recovering and treating sodium acetate in oil by-products. Through the system and the recovery process of the present invention, after the oil, acidic substances and oil phase in the crude sodium acetate aqueous solution are effectively removed, the sodium acetate aqueous solution with a water content of 90% is evaporated to a crystallization concentration through a triple-effect evaporator, and sodium acetate trihydrate is produced by crystallization. The triple-effect evaporator saves about 70% of energy compared with the single-effect evaporator.

In order to achieve the above object, the technical solution adopted by the present invention is:

A sodium acetate recovery and treatment system in oil by-products comprises a sodium acetate aqueous solution decolorization process, a sodium acetate aqueous solution filtration process, a pH adjustment process, and a sodium acetate aqueous solution evaporation process.

Furthermore, the sodium acetate aqueous solution decolorization process includes a premixing tank for mixing the sodium acetate aqueous solution and activated carbon, a decolorization tower connected to the outlet of the premixing tank, and raw materials pumped out from the outlet of the decolorization tower by a centrifugal pump and sent to the sodium acetate aqueous solution filtration and pH adjustment process.

Furthermore, the sodium acetate aqueous solution needs to be heat exchanged with steam in the first plate heat exchanger before entering the premixing tank. A liquid foam collector is provided on the top of the bleaching tower. The raw materials in the liquid outlet pipe at the bottom of the bleaching tower are divided into two paths and heat exchanged with 4bar steam respectively, and then sent to the sodium acetate aqueous solution filtration and pH adjustment process through a centrifugal pump for standby.

Furthermore, the sodium acetate aqueous solution filtration and pH adjustment process includes a blade filter, the bottom outlet of the blade filter is connected to the Jiaolong conveyor, and the blade filter is provided with a discharge port and a feed port. The feed port is located at the bottom of the blade filter, and a discharge port is provided in the middle of the blade filter to directly send the material to the material storage tank. It also includes an alkali liquid tank, and the alkali liquid outlet of the alkali liquid tank is sent into the blade filter discharge port pipeline through a metering pump to adjust the pH value of the sodium acetate aqueous solution.

Furthermore, an outlet pipeline is provided on the upper part of the blade filter, and a purge pipeline is provided on the outlet pipeline, and the purge pipeline is connected to a 4bar saturated steam pipeline. A water vapor separator is provided at the end of the outlet pipeline, and a liquid outlet is provided at the bottom of the water vapor separator, and the liquid outlet is connected to a turbid water tank. A gas outlet is provided on the upper part of the water vapor separator, and a cake blowing condenser is provided at the end of the gas outlet. The outlet of the turbid water tank sends the material to the decolorization tank in the sodium acetate decolorization section through a centrifugal pump for further decolorization. The feed port and the discharge port pipeline of the blade filter are both provided with bypasses, and the bypasses are both connected to the turbid water tank. The blade filter is also provided with an air inlet, and the air inlet is connected to a 6bar compressed air pipeline. There are two blade filters, and the two blade filters are arranged in parallel, and also include a filter plate washing tank.

Furthermore, the sodium acetate aqueous solution evaporation process includes that after the raw material enters the feed tank, it is sent to the second plate heat exchanger through the triple-effect feed pump for heat exchange, and then sent to the triple-effect separator through the bottom outlet pipe to flow into the triple-effect heater, the triple-effect heater is sent to the second-effect separator through the second-effect feed pump at the bottom, the raw material of the second-effect separator flows into the second-effect heater through its bottom pipe, the second-effect heater flows into the first-effect separator through the first-effect feed pump, the first-effect separator is sent into the first-effect heater through its bottom discharge pipe and the first-effect circulation pump, the generated gas is sent to the first-effect separator for further separation, when the raw material concentration reaches a certain value, the first-effect discharge pump is turned on, the raw material is sent to the crystallization tank for crystallization, the crystallized raw material is sent to the centrifuge for separation, the solid coming out of the centrifuge is sent to the product section for packaging, the liquid is sent to the buffer tank for temporary storage, and is sent to the decolorization section by a pump to enter the filtration again and participate in the crystallization again.

Furthermore, the buffer tank is provided with a buffer pump, which delivers the buffer to other work sections or discharges it externally. It also includes a machine sealing water tank, which delivers cooling water to the buffer pump, the first-effect discharge pump, the first-effect circulation pump, the first-effect feed pump, the second-effect feed pump, and the third-effect feed pump respectively through a sealing water pump. After cooling, the cooling water flows back into the machine sealing water tank through a recovery pipeline for reuse. It also includes a surface condenser. The heat source of the surface condenser comes from the steam separated by the three-effect separator. A cooling water inlet and a cooling water outlet are provided on the surface condenser. The outlet pipe at the bottom of the surface condenser is connected to the surface cold water sealing tank. The first-effect heater, the second-effect heater and the three-effect heater The condensate in the device is connected with the surface cooling water sealing tank, and part of the water in the surface cooling water sealing tank is mixed with the hot steam at the top of the three-effect separator and enters the surface condenser for further utilization. Another part of the water in the surface cooling water sealing tank is sent to the condensation water tank through the condensation water pump and used as the cold source of the second plate heat exchanger. A vacuum pump is provided at the bottom of the surface condenser, the cooling water inlet of the condensation water pump is connected with the water outlet of the sealing water pump, and the outlet of the condensation water pump is connected with the machine sealing water tank. The first-effect heater is also provided with a heating steam inlet, the steam channel at the top of the first-effect separator is connected with the second-effect heater, and the steam channel at the top of the second-effect separator is connected with the three-effect heater.

Furthermore, before entering the premixing tank, the sodium acetate aqueous solution is first subjected to a precipitation and impurity removal process to remove impurities in the sodium acetate aqueous solution. The sodium acetate aqueous solution after impurity removal passes through a first plate heat exchanger and then enters the premixing tank.

The present invention also provides a process for recovering sodium acetate using the above system, the process comprising the following steps:

1) The crude sodium acetate aqueous solution from the acidification section is sent to the sodium acetate aqueous solution decolorization process, and the grease, colloid and acidic substances contained therein are removed by the adsorption of activated carbon;

2) sending the mixed solution of the sodium acetate aqueous solution and activated carbon which has been decolorized in step 1) to a sodium acetate aqueous solution filtration and pH adjustment process, filtering it through a leaf filter, and then adjusting the pH value to 7 to obtain a neutral sodium acetate aqueous solution;

3) The sodium acetate aqueous solution from step 2) is sent to the sodium acetate aqueous solution evaporation process for evaporation and crystallization to obtain sodium acetate crystals with a water content of 5%.

Furthermore, in step 1), before the activated carbon adsorption, the pH of the crude sodium acetate aqueous solution is adjusted to 6-9, and the temperature is controlled to 60-70°C during the adjustment.

Furthermore, in step 1), the amount of activated carbon added is 1-10% of the amount of the sodium acetate aqueous solution, and the decolorization time is 1-2 hours.

Furthermore, in step 2), the solid activated carbon treated by the leaf filter is sent to a fermentation tower for fermentation, and after fermentation, it is finally mixed and sold as a fertilizer.

Furthermore, in step 3), the evaporation is carried out by a triple-effect evaporator, the vacuum degree of the triple-effect evaporation is controlled to be 90-100 Pa, the vacuum degree of the second-effect evaporation is controlled to be 70-80 Pa, the vacuum degree of the first-effect evaporation is controlled to be 40-50 Pa, the first-effect evaporation temperature is 75-80° C., and the evaporated sodium acetate concentrate is 25-35° Bé.

Furthermore, in step 3), the crystallization temperature is 55-60° C., and the crystallization time is 4-48 hours.

Furthermore, the crystallized liquid in step 3) is centrifuged and dried to obtain sodium acetate trihydrate with a water content of less than 5%, and the obtained mother liquor is recycled again, and the centrifugal speed is 1400-1900rpm.

In summary, since the present invention adopts the above technical solution, the present invention has the following beneficial effects:

1. After the crude sodium acetate aqueous solution is decolorized by the sodium acetate aqueous solution, the oil phase, acidic substances and impurities in the crude sodium acetate aqueous solution are loaded on the activated carbon, so that the sodium acetate aqueous solution is further purified to provide a strong help for the subsequent evaporation, and the activated carbon adsorbed with the oil phase, acidic substances and impurities can be sent to the fermentation section for fermentation and continued to be used as an organic fertilizer, without the generation of waste, which is environmentally friendly.

2. Setting of the sodium acetate aqueous solution filtration and pH adjustment process: The sodium acetate aqueous solution from the previous process, i.e., the sodium acetate aqueous solution decolorization process, is further separated by the leaf filter, and then adjusted by the alkali liquid tank, so that the purity obtained in the subsequent preparation of sodium acetate crystals is higher, which increases its added value. The air path connected to the 6bar compressed steam pipeline provided by the leaf filter ensures that the solid matter on the filter plate can be smoothly blown down to prevent clogging. The sodium acetate solution coming out of the leaf filter is adjusted by the alkali liquid in the alkali liquid tank to facilitate the treatment of the later evaporation process. The whole device is tightly connected and easy to use.

3. A triple-effect evaporator is used to evaporate and crystallize the sodium acetate aqueous solution. The principle of triple-effect evaporation is an evaporation operation after the combination of three evaporators. When the triple-effect evaporator is in operation, the pressure of the after-effect and the boiling point of the solution are required to be lower than those of the front-effect evaporator. The secondary steam of the front-effect is introduced as the heating medium of the after-effect, that is, the heating chamber of the after-effect becomes the condenser of the secondary steam of the front-effect. The first effect needs to consume the steam of the boiler. The triple-effect evaporation saves about 70% of energy compared with the single-effect evaporator. In addition, the final steam of the triple-effect separator in this application goes to the surface condenser for condensation, and the condensed liquid with a certain temperature is sent to the surface cold water sealing tank to continue to mix with the steam of the triple-effect separator. On the one hand, the workload of the surface condenser is reduced, and on the other hand, the waste heat of the entire system is recycled and reused, which makes full use of the heat of the entire system and reduces heat loss.

4. The present invention effectively connects various processes, so that the purity of the final sodium acetate product is greatly improved, and the water content is reduced from 90% to 5%, which effectively solves the problem of resource utilization of sodium salt in the processing of oil by-products;

5. The crude sodium acetate aqueous solution of the present invention is first subjected to a precipitation and impurity removal process before entering the premixing tank, and solid impurities in the crude sodium acetate are removed before the activated carbon decolorization, thereby further improving the decolorization effect of the crude sodium acetate solution.

6. Before the crude sodium acetate aqueous solution of the present invention is subjected to activated carbon decolorization, the pH of the crude sodium acetate aqueous solution is first adjusted to 6-9, and activated carbon is added under this pH condition to adsorb and remove the oil phase, acidic substances and impurities contained in the crude sodium acetate, so that the decolorization effect of the crude sodium acetate is greatly improved; at the same time, the evaporation process of the sodium acetate aqueous solution controls the COD of the condensed water generated by evaporation to 300-450 mg/L, thereby greatly reducing the pollution to the environment.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a schematic structural diagram of a sodium acetate aqueous solution decolorization process in the present invention;

FIG2 is a schematic structural diagram of the sodium acetate aqueous solution filtration and pH adjustment process in the present invention;

FIG3 is a schematic structural diagram of the evaporation process of the sodium acetate aqueous solution in the present invention;

FIG. 4 is a schematic structural diagram of a system for recovering and treating sodium acetate in oil by-products according to the present invention.

DETAILED DESCRIPTION

In order to make the purpose, technical solution and advantages of the present invention more clearly understood, preferred embodiments are given below to further describe the present invention in detail. However, it should be noted that many details listed in the specification are only for the purpose of enabling the reader to have a thorough understanding of one or more aspects of the present invention, and these aspects of the present invention can be implemented even without these specific details.

Example 1

As shown in Figures 1 to 4, a sodium acetate recovery and treatment system in oil by-products includes a sodium acetate aqueous solution decolorization process, a sodium acetate aqueous solution filtration and pH adjustment process, and a sodium acetate aqueous solution evaporation process. The sodium acetate aqueous solution decolorization process includes a premixing tank 111 for mixing the sodium acetate aqueous solution and activated carbon, a decolorization tower 112 connected to the outlet of the premixing tank 111, and raw materials pumped out from the outlet of the decolorization tower 112 through a centrifugal pump 113 and sent to the sodium acetate aqueous solution filtration and pH adjustment process. The pH adjustment process adopts an online pH sensor for online automatic adjustment, which can achieve the effect of continuous feeding processing. Before entering the premixing tank 111, the sodium acetate aqueous solution needs to exchange heat with steam in the first plate heat exchanger 114 and then enter the premixing tank 111. A liquid foam collector 115 is provided on the top of the bleaching tower 112 to collect the liquid foam and volatilized acetic acid waste gas in the tank, and condense the waste gas before sending it to the tail gas treatment system for treatment. The decolorization process takes 1-2 hours. The raw materials at the bottom of the liquid outlet pipe of the bleaching tower 112 are divided into two paths and exchanged with 4bar steam respectively, and then sent to the sodium acetate aqueous solution filtration and pH adjustment process through a centrifugal pump 113 for standby.

Before entering the premixing tank 111, the sodium acetate aqueous solution first undergoes a precipitation and impurity removal process to remove impurities in the sodium acetate aqueous solution. The sodium acetate aqueous solution after impurity removal passes through the first plate heat exchanger 114 and then enters the premixing tank 111. In the present invention, the crude sodium acetate aqueous solution first enters the precipitation tank 117 for precipitation before the activated carbon decolorization treatment, and then enters the impurity removal tank 118 for impurity removal after the precipitation is completed. After the precipitation and impurity removal, the crude sodium acetate aqueous solution passes through the first plate heat exchanger 114 for heat exchange and then enters the premixing tank 111, and then undergoes the subsequent activated carbon decolorization and other treatment processes.

The sodium acetate aqueous solution filtration and pH adjustment process includes a blade filter 121, the bottom outlet of the blade filter 121 is connected to the Jiaolong conveyor, and the solid material from the outlet of the blade filter 121 is sent to the microbial fermentation tank for biocomposting. The blade filter 121 is provided with a discharge port 122 and a feed port 123, and the feed port 123 is located at the bottom of the blade filter 121. The blade filter 121 is provided with a discharge port 122 in the middle to directly send the material to the material storage tank 124, and also includes an alkali liquid tank 125. The outlet of the alkali liquid tank 125 sends the alkali liquid into the blade filter 121 through a metering pump 126 for discharge. The pH value of the sodium acetate aqueous solution is adjusted by an inlet pipe. An outlet pipe 127 is also provided on the upper part of the leaf filter 121. A purge pipe is provided on the outlet pipe 127. The purge pipe 128 is connected to a 4 bar saturated steam pipe. The purge pipe 128 is used to send the gas-liquid mixture inside the leaf filter 121 to a water-gas separator 129 for further separation. A water-gas separator 129 is provided at the end of the outlet pipe 127. A liquid outlet is provided at the bottom of the water-gas separator 129. The liquid outlet is connected to the turbid water tank 1210. A gas outlet is provided on the upper part of the water-gas separator 129. A purge pipe is provided at the end of the gas outlet. Condenser 1211, the outlet of the turbid water tank 1210 is used to send the material to the decolorization tank in the sodium acetate decolorization section for further decolorization through a centrifugal pump. The feed port and the discharge port pipeline of the blade filter 121 are both provided with bypasses, which are both connected to the turbid water tank 1210. The blade filter 121 is also provided with an air inlet, which is connected to a 6 bar compressed steam pipeline. There are two blade filters 121, which are arranged in parallel. The outlet pipeline of the alkali liquid tank 125 is also provided with a spare quantitative pump 126 for standby use when the equipment fails. It also includes a filter plate washing tank 1212 for cleaning the filter plate. The filter plate of the blade filter 121 of the device is arranged to further separate the sodium acetate aqueous solution from the previous process section, i.e., the sodium acetate aqueous solution decolorization process section, through the blade filter, and then through the regulation of the alkali liquid tank 125, so that the purity obtained in the subsequent preparation of sodium acetate crystals is higher, thereby increasing its added value. The air path connected to the 6 bar compressed steam pipeline provided in the blade filter ensures that the solid matter on the filter plate can be smoothly blown down to prevent clogging. The sodium acetate solution coming out of the blade filter is regulated by the alkali liquid in the alkali liquid tank to facilitate the processing of the subsequent evaporation process. The whole device is tightly connected and easy to use.

The sodium acetate aqueous solution filtration and pH adjustment process also includes a bag filter 130, the feed port of the bag filter 130 is connected to the discharge port 122 of the blade filter 121, the discharge port of the bag filter 130 is connected to the material storage tank 124, and the alkali liquid discharge port of the alkali liquid tank 125 sends the alkali liquid into the material storage tank 124 through the metering pump 126 to adjust the pH value of the sodium acetate aqueous solution.

In the sodium acetate aqueous solution evaporation process, when the equipment is not running, the raw material first enters the feed tank 131 and is then sent to the second plate heat exchanger 133 through the triple-effect feed pump 132 for heat exchange, and then sent to the triple-effect separator 4 through the bottom outlet pipe to flow into the triple-effect heater 135. The triple-effect heater 135 is sent to the second-effect separator 137 through the second-effect feed pump 136 at the bottom. The raw material of the second-effect separator 137 flows into the second-effect heater 8 through the bottom pipe. The second-effect heater 138 flows into the first-effect separator 1310 through the first-effect feed pump 139. The first-effect separator 1310 is fed into the first-effect heater 1312 through the bottom discharge pipe and the first-effect circulation pump 1311, and the generated gas is fed into the first-effect separator 1310 for further separation. When the raw material concentration reaches a certain value, the first-effect discharge pump is turned on to send the raw material to the crystallization tank for crystallization, and the crystallized raw material is sent to the centrifuge 1315 for separation. The solid coming out of the centrifuge 1315 is sent to the product section for packaging, and the liquid is sent to the buffer tank 1316 for temporary storage, and then sent to the decolorization section by a pump to enter the filtration again and participate in crystallization again. There are multiple crystallization tanks, which adopt a multi-tank parallel mode, which can meet the crystallization operation of multiple batches of raw material concentrates at the same time, thereby improving the production efficiency of the system of the present invention. The crystallization tank contains an anchor-type stirring paddle, and the inner wall of the tank is made of enamel material, which can reduce the wall adhesion phenomenon of sodium acetate crystals and improve the product yield. The crystallization tank is set to automatically control the cooling rate. By adjusting the cooling rate and the stirring speed, the crystallization time is controlled within 4-48 hours according to the condition of the concentrated liquid and the crystallization curve. After the crystallization is completed, it is sent to a centrifuge for separation through a feeding pump. A temperature sensor is also arranged in the tank body for monitoring the crystallization cooling curve.

The buffer tank 1316 is provided with a buffer pump, and the buffer pump 1317 sends the buffer to other sections or discharges it. It also includes a machine sealing water tank 1318. The machine sealing water tank 1318 sends cooling water to the buffer pump 1317, the first-effect discharge pump 1313, the first-effect circulation pump 1311, the first-effect feed pump 139, the second-effect feed pump 136, and the third-effect feed pump 132 through the sealing water pump 1319. After cooling, it flows back into the machine sealing water tank 1318 through the recovery pipeline for reuse. The buffer pump 1317, the first-effect discharge pump 1313, the first-effect circulation pump 1311, the first-effect feed pump 139, the second-effect feed pump 136, and the third-effect feed pump 132 are all high-temperature pumps, which need to be cooled after long-term use. It also includes a surface condenser 1320. The heat source of the surface condenser 1320 comes from the three-effect separator 134 is separated from the steam, and the surface condenser 1320 is provided with a cooling water inlet and a cooling water outlet. The water outlet pipe at the bottom of the surface condenser 1320 is connected to the surface cold water sealing tank 1321. The condensate in the first effect heater 1312, the second effect heater 138 and the third effect heater 135 are all connected to the surface cold water sealing tank 1321, and a part of the water in the surface cold water sealing tank 1321 is mixed with the hot steam at the top of the three-effect separator 4 and enters the surface condenser 1320 for further use. Another part of the water in the surface cold water sealing tank 1321 is sent to the condensation water tank 1323 through the condensation water pump 1322 as the cold source of the second plate heat exchanger 133. A vacuum pump 1324 is provided at the bottom of the surface condenser 1320. The vacuum pump 1324 is used to adjust the vacuum degree of the entire system. The condensation water pump 1322 The cooling water inlet is connected to the outlet of the sealing water pump 1319, the outlet of the condensing water pump 1322 is connected to the machine sealing water tank 1318, the first-effect heater 1312 is also provided with a heating steam inlet, the steam channel at the top of the first-effect separator 1310 is connected to the second-effect heater 138, and the steam channel at the top of the second-effect separator 137 is connected to the triple-effect heater 135. This arrangement can make full use of the steam of the previous effect as the heating medium of the subsequent effect, and make full use of the heat. When used specifically, the first-effect heater heats the medium by passing in high-temperature steam, and the liquid level decreases after a part of the liquid evaporates, and the discharge liquid level of the finished product is further reduced. When it is reduced to a set height, the first-effect separator sends the raw materials into the first-effect heater through the first-effect circulation pump for continued reaction, and the subsequent second-effect heater further sends the raw materials through The first-effect feed pump feeds the first-effect separator, and the second-effect separator feeds the raw materials into the second-effect heater, so that the three-effect heater feeds the raw materials into the second-effect separator through the second-effect feed pump, and the three-effect separator further replenishes the raw materials into the three-effect heater, so that the feed tank feeds the raw materials into the three-effect separator through the three-effect feed pump, and the raw materials are replenished layer by layer. The raw materials are preliminarily heated in the after-effect heater to reduce the workload of the front-effect heater. The principle of three-effect evaporation is an evaporation operation after the combination of three evaporators. When the three-effect evaporator is in operation, the pressure of the after-effect and the boiling point of the solution are required to be lower than those of the front-effect evaporator. The secondary steam of the front effect is introduced as the heating medium of the after-effect, that is, the heating chamber of the after-effect becomes the condenser of the secondary steam of the front effect. The first effect needs to consume the steam from the live boiler. The three-effect evaporation saves about 70% of energy compared with the single-effect evaporator.

Example 2

This embodiment provides a process for recovering sodium acetate using the system of embodiment 1, and the process comprises the following steps:

1) Adding 50% liquid caustic soda to adjust the pH of the crude sodium acetate aqueous solution from the acidification section to adjust the pH value to 6, and controlling the temperature at 60° C. Sending the obtained crude sodium acetate aqueous solution with a pH value of 6 to a sodium acetate aqueous solution decolorization process, adding activated carbon for decolorization, the amount of activated carbon added is 1% of the amount of the sodium acetate aqueous solution, and the decolorization time is 2 hours. The adsorption of the activated carbon can remove the grease, colloid and acidic substances contained in the crude sodium acetate solution to obtain a raw material mixed solution;

2) sending the mixed solution of the sodium acetate aqueous solution and activated carbon which has been decolorized in step 1) to the sodium acetate aqueous solution filtration and pH adjustment process, filtering it through a blade filter, and then adjusting the pH value to 7 with an alkali solution to obtain a neutral sodium acetate aqueous solution, wherein the alkali solution is a 50% alkali solution, and the waste gas generated by the pH adjustment enters the absorption tower through an air suction device for absorption and then is discharged;

3) The sodium acetate aqueous solution from step 2) is sent to the sodium acetate aqueous solution evaporation process, and a triple-effect evaporator is used for evaporation, and the vacuum degree of the triple-effect evaporation is controlled to be 90 Pa, the vacuum degree of the second-effect evaporation is controlled to be 70 Pa, and the vacuum degree of the first-effect evaporation is controlled to be 40 Pa. The temperature of the first-effect evaporation is controlled to be 75° C. When the evaporated sodium acetate concentrate reaches 25° Bé, it is sent to a crystallization tank for crystallization, and the crystallization temperature is controlled to be 55° C. The crystallization time is 4 hours. The crystallized feed liquid is centrifuged to obtain sodium acetate crystals with a moisture content of 5%. The obtained mother liquor is recycled and reused again, and the centrifugal speed is controlled to be 1400 rpm.

Example 3

This embodiment provides a process for recovering sodium acetate using the system of embodiment 1, and the process comprises the following steps:

This embodiment provides a process for recovering sodium acetate using the system of embodiment 1, and the process comprises the following steps:

1) Adding 50% liquid caustic soda to adjust the pH of the crude sodium acetate aqueous solution from the acidification section to adjust the pH value to 8, and controlling the temperature at 65° C.; sending the obtained crude sodium acetate aqueous solution with a pH value of 8 to a sodium acetate aqueous solution decolorization process, adding activated carbon for decolorization, the amount of activated carbon added is 5% of the amount of the sodium acetate aqueous solution, the decolorization time is 1.5 hours, and the adsorption effect of the activated carbon can remove the grease, colloid and acidic substances contained in the crude sodium acetate solution to obtain a raw material mixed solution;

2) sending the mixed solution of the sodium acetate aqueous solution and activated carbon which has been decolorized in step 1) to the sodium acetate aqueous solution filtration and pH adjustment process, filtering it through a blade filter, and then adjusting the pH value to 7 to obtain a neutral sodium acetate aqueous solution, and the waste gas generated by the pH adjustment enters the absorption tower through an air suction device for absorption and then is discharged;

3) The sodium acetate aqueous solution from step 2) is sent to the sodium acetate aqueous solution evaporation process, and a triple-effect evaporator is used for evaporation, and the vacuum degree of the triple-effect evaporation is controlled to be 95 Pa, the vacuum degree of the second-effect evaporation is controlled to be 75 Pa, and the vacuum degree of the first-effect evaporation is controlled to be 45 Pa. The first-effect evaporation temperature is controlled to be 75° C. When the evaporated sodium acetate concentrate reaches 30° Bé, it is sent to a crystallization tank for crystallization, and the crystallization temperature is controlled to be 57° C. The crystallization time is 13 hours. The crystallized feed liquid is centrifuged to obtain sodium acetate crystals with a moisture content of 5%, and the obtained mother liquor is recycled and reused again, and the centrifugal speed is controlled to be 1600 rpm.

Example 4

This embodiment provides a process for recovering sodium acetate using the system of embodiment 1, and the process comprises the following steps:

1) Adding 50% liquid caustic soda to adjust the pH of the crude sodium acetate aqueous solution from the acidification section to adjust the pH value to 9, and controlling the temperature at 70° C. Sending the obtained crude sodium acetate aqueous solution with a pH value of 9 to a sodium acetate aqueous solution decolorization process, adding activated carbon for decolorization, the amount of activated carbon added is 10% of the amount of the sodium acetate aqueous solution, and the decolorization time is 1 hour. The adsorption of the activated carbon can remove the grease, colloid and acidic substances contained in the crude sodium acetate solution to obtain a raw material mixed solution;

2) sending the mixed solution of the sodium acetate aqueous solution and activated carbon which has been decolorized in step 1) to the sodium acetate aqueous solution filtration and pH adjustment process, filtering it through a blade filter, and then adjusting the pH value to 8 to obtain an alkaline sodium acetate aqueous solution, and the waste gas generated by the pH adjustment enters the absorption tower through an air suction device for absorption and then is discharged;

3) The sodium acetate aqueous solution from step 2) is sent to the sodium acetate aqueous solution evaporation process, and a triple-effect evaporator is used for evaporation, and the vacuum degree of the triple-effect evaporation is controlled to be 100 Pa, the vacuum degree of the second-effect evaporation is controlled to be 80 Pa, and the vacuum degree of the first-effect evaporation is controlled to be 50 Pa. The temperature of the first-effect evaporation is controlled to be 80° C. When the evaporated sodium acetate concentrate reaches 35° Bé, it is sent to a crystallization tank for crystallization, and the crystallization temperature is controlled to be 60° C. The crystallization time is 48 hours. The crystallized feed liquid is centrifuged to obtain sodium acetate crystals with a moisture content of 5%. The obtained mother liquor is recycled and reused again, and the centrifugal speed is controlled to be 1900 rpm.

Comparative Example 1

The difference between this comparative example and Example 4 is that in step 1), the pH value is adjusted to 11, and the remaining steps and process parameters are the same as those of Example 4.

Comparative Example 2

The difference between this comparative example and Example 4 is that in step 1), the pH value is adjusted to 10, and the remaining steps and process parameters are the same as those of Example 4.

Comparative Example 3

The difference between this comparative example and Example 4 is that in step 1), the pH value is adjusted to 4, and the remaining steps and process parameters are the same as those of Example 4.

Comparative Example 4

The difference between this comparative example and Example 4 is that in step 1), the pH value is adjusted to 2, and the remaining steps and process parameters are the same as those of Example 4.

Through the test implementation of Example 2-Example 4 and Comparative Examples 1-4, the yield of the obtained sodium acetate, the whiteness of the sodium acetate crystals, and the COD of the condensed water were detected. The specific data are shown in Table 1:

Table 1

Example Yield (%) Whiteness(%) COD(mg/L) Example 2 75.85 82 446 Example 3 77.68 85 384 Example 4 79.98 87 309 Comparative Example 1 67.25 62 768 Comparative Example 2 69.68 59 859 Comparative Example 3 57.75 66 948 Comparative Example 4 55.28 63 927

It can be concluded from the above table that the recovery of sodium acetate from oil by-products using the recovery system and process method has a high yield, and the whiteness of the product basically meets the market requirements, and the COD of the evaporated condensed water is basically controlled at 300-450 mg/L. At the same time, it can be seen from Comparative Examples 1-4 that the yield of the product is lower than that of Example 4, and the whiteness value is much lower than the whiteness obtained in Example 4. This may be due to the fact that the adsorption effect of the activated carbon under the conditions of the comparative example is lower than the adsorption effect under the conditions proposed in Example 4, resulting in the impurities contained in the sodium acetate not being completely adsorbed and removed, resulting in a decrease in the yield and whiteness in the comparative example.

The above description is only a preferred embodiment of the present invention and does not limit the present invention in other forms. Any technician familiar with the profession may use the technical content explained above to change or modify it into an equivalent embodiment with equivalent changes for use in other fields. However, any simple modification, equivalent change and modification made to the above embodiment based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still falls within the scope of protection of the technical solution of the present invention.

Claims (5)

1. A process for recovering sodium acetate from oil by-products, characterized in that it comprises a sodium acetate aqueous solution decolorization process, a sodium acetate aqueous solution filtration process, a pH adjustment process, and a sodium acetate aqueous solution evaporation process; The process for recovering sodium acetate comprises the following steps: 1) The crude sodium acetate aqueous solution from the acidification section is sent to the sodium acetate aqueous solution decolorization process, and the grease, colloid and acidic substances contained therein are removed by the adsorption of activated carbon; 2) sending the mixed solution of the sodium acetate aqueous solution and activated carbon which has been decolorized in step 1) to a sodium acetate aqueous solution filtration and pH adjustment process, filtering it through a leaf filter, and then adjusting the pH value to 7 to obtain a neutral sodium acetate aqueous solution; 3) sending the sodium acetate aqueous solution from step 2) to a sodium acetate aqueous solution evaporation process for evaporation and crystallization to obtain sodium acetate crystals with a water content of 5%; In step 1), before adsorption on activated carbon, the pH of crude sodium acetate aqueous solution is adjusted to 6-9, and the temperature is controlled to 60-70°C during the adjustment; The sodium acetate aqueous solution decolorization process includes using a premixing tank for mixing the sodium acetate aqueous solution and activated carbon, a decolorization tower connected to the outlet of the premixing tank, and extracting the sodium acetate aqueous solution from the outlet of the decolorization tower through a centrifugal pump and sending it to the sodium acetate aqueous solution filtration and pH adjustment process; The sodium acetate aqueous solution needs to be heat exchanged with steam in the first plate heat exchanger before entering the premixing tank. A liquid foam collector is provided on the top of the decolorizing tower. The raw materials of the liquid outlet pipe at the bottom of the decolorizing tower are divided into two paths and heat exchanged with 4bar steam respectively, and then sent to the sodium acetate aqueous solution filtration and pH adjustment process through a centrifugal pump for standby; The sodium acetate aqueous solution filtering and pH adjustment process includes the use of a blade filter, the bottom outlet of the blade filter is connected to a Jiaolong conveyor, a discharge port and a feed port are provided on the blade filter, the feed port is located at the bottom of the blade filter, a discharge port is provided in the middle of the blade filter to directly send the material to the material storage tank, and also includes an alkali liquid tank, the alkali liquid outlet of the alkali liquid tank is sent into the blade filter discharge port pipeline through a metering pump to adjust the pH value of the sodium acetate aqueous solution. 2. The process for recovering sodium acetate in grease by-products as claimed in claim 1, characterized in that an outlet pipeline is further provided on the upper portion of the leaf filter, a purge pipeline is provided on the outlet pipeline, the purge pipeline is connected to a saturated steam pipeline of 4 bar, a water vapor separator is provided at the end of the outlet pipeline, a liquid outlet is provided at the bottom of the water vapor separator, the liquid outlet is connected to a turbid water tank, a gas outlet is provided on the upper portion of the water vapor separator, a cake blowing condenser is provided at the end of the gas outlet, the turbid water tank outlet sends the material into the decolorizing tank in the sodium acetate decolorizing section for further decolorization by a centrifugal pump, a bypass is provided on the feed inlet and the discharge outlet pipeline of the leaf filter, the bypass is connected to the turbid water tank, the leaf filter is also provided with an air inlet, the air inlet is connected to a compressed air pipeline of 6 bar, there are two leaf filters, the two leaf filters are arranged in parallel, and also include a filter plate washing tank. 3. The process for recovering sodium acetate in oil by-products as claimed in claim 2, characterized in that the sodium acetate aqueous solution evaporation process comprises using the raw material to enter the feed tank and then be sent to the second plate heat exchanger through a triple-effect feed pump for heat exchange, and then be sent to the triple-effect separator through the bottom outlet pipe to flow into the triple-effect heater, the triple-effect heater is sent into the second-effect separator through the second-effect feed pump at its bottom, the raw material of the second-effect separator flows into the second-effect heater through its bottom pipeline, the second-effect heater flows into the first-effect separator through the first-effect feed pump, the first-effect separator is sent into the first-effect heater through its bottom discharge pipe and the first-effect circulation pump, the generated gas is sent to the first-effect separator for continued separation, when the raw material concentration reaches a certain value, open the first-effect discharge pump, send the raw material to the crystallization tank for crystallization, send the crystallized raw material to the centrifuge for separation, the solid coming out of the centrifuge is sent to the product section for packaging, the liquid is sent to the buffer tank for temporary storage, and is sent to the decolorization section by a pump to enter the filtration again and participate in crystallization again. 4. The process for recovering sodium acetate in oil by-products as claimed in claim 3 is characterized in that the buffer tank is provided with a buffer pump, which delivers the buffer to other sections or discharges it externally, and also includes a machine sealing water tank, which delivers cooling water to the buffer pump, the first-effect discharge pump, the first-effect circulation pump, the first-effect feed pump, the second-effect feed pump, and the third-effect feed pump respectively through a sealing water pump, and the cooling water is then refluxed into the machine sealing water tank through a recovery pipeline for reuse after cooling, and also includes a surface condenser, the heat source of the surface condenser comes from the steam separated by the three-effect separator, the surface condenser is provided with a cooling water inlet and a cooling water outlet, the outlet pipe at the bottom of the surface condenser is connected to the surface cold water sealing tank, and the first The condensate in the first-effect heater, the second-effect heater and the third-effect heater are all connected with the surface cooling water seal tank, and part of the water in the surface cooling water seal tank is mixed with the hot steam at the top of the three-effect separator and enters the surface condenser for further utilization. Another part of the water in the surface cooling water seal tank is sent to the condensation water tank through the condensation water pump and used as the cold source of the second plate heat exchanger. A vacuum pump is provided at the bottom of the surface condenser, the cooling water inlet of the condensation water pump is connected with the water outlet of the sealing water pump, and the outlet of the condensation water pump is connected with the machine sealing water tank. The first-effect heater is also provided with a heating steam inlet, the steam channel at the top of the first-effect separator is connected with the second-effect heater, and the steam channel at the top of the second-effect separator is connected with the three-effect heater. 5. The process for recovering sodium acetate in oil by-products according to any one of claims 3 to 4, characterized in that the sodium acetate aqueous solution is first subjected to a precipitation and impurity removal process before entering the premixing tank to remove impurities in the sodium acetate aqueous solution, and the sodium acetate aqueous solution after impurity removal enters the premixing tank after heat exchange through a first plate heat exchanger.