阅读说明：本技术 生物柴油酸碱两步法中气相甲醇分级回收工艺 (Gas-phase methanol grading recovery process in biodiesel acid-base two-step method ) 是由 张少敏 王�琦 娄源民 于 2021-11-15 设计创作，主要内容包括：本发明公开了一种生物柴油酸碱两步法中气相甲醇分级回收工艺,涉及气相甲醇回收技术领域,所述工艺包括以下步骤,通过第一冷凝器对酯化釜气相出口产生的弛放气进行冷凝；通过在线水分测定仪对冷凝液中甲醇浓度进行分析确定后分级收集；将低浓度甲醇罐中的低浓度甲醇送入甲醇精馏系统进行精馏得到的高浓度甲醇；将高浓度甲醇罐中高浓度甲醇直接循环使用,即,通入甲醇气化器气化后进入酯化釜。该生物柴油酸碱两步法中气相甲醇分级回收工艺,一方面降低了甲醇精馏系统处理量,从而减小甲醇精馏系统设备规格,降低投资；另一方面,避免了“重复劳动”,降低了甲醇精馏能耗。(The invention discloses a gas-phase methanol fractional recovery process in a biodiesel acid-base two-step method, which relates to the technical field of gas-phase methanol recovery, and comprises the following steps of condensing purge gas generated at a gas-phase outlet of an esterification kettle by a first condenser; analyzing and determining the concentration of methanol in the condensate by an online moisture tester, and then collecting the condensate in stages; sending the low-concentration methanol in the low-concentration methanol tank into a methanol rectification system for rectification to obtain high-concentration methanol; directly recycling high-concentration methanol in the high-concentration methanol tank, namely introducing the methanol into a methanol gasifier for gasification and then introducing the methanol into an esterification kettle. According to the gas-phase methanol fractional recovery process in the biodiesel acid-base two-step method, on one hand, the treatment capacity of a methanol rectification system is reduced, so that the equipment specification of the methanol rectification system is reduced, and the investment is reduced; on the other hand, the repeated labor is avoided, and the energy consumption of the methanol rectification is reduced.)

1. A gas phase methanol grading recovery process in a biodiesel acid-base two-step method is characterized in that: the process comprises the following steps:

step a: the purge gas generated at the gas phase outlet of the esterification kettle (33) is condensed by a first condenser (4);

step b: analyzing and determining the concentration of the methanol in the condensate by an online moisture tester (5), and storing the condensate into a low-concentration methanol tank (8) and a high-concentration methanol tank (9) in a classified manner according to the concentration of the methanol in the condensate;

step c: sending the low-concentration methanol in the low-concentration methanol tank (8) into a methanol rectification system for rectification, and conveying the rectified high-concentration methanol into a high-concentration methanol tank (9);

step d: high-concentration methanol in the high-concentration methanol tank (9) is introduced into the methanol gasifier (2) to be gasified and then enters the esterification kettle (3).

2. The gas-phase methanol fractional recovery process in a biodiesel acid-base two-step process according to claim 1, characterized in that: the condensate in step b is obtained by condensing the purge gas from step a.

3. The gas-phase methanol fractional recovery process in a biodiesel acid-base two-step process according to claim 1, characterized in that: the inlet of low concentration methyl alcohol jar (8) is equipped with first automatic cutout valve (6), the inlet of high concentration methyl alcohol jar (9) is equipped with second automatic cutout valve (7), first automatic cutout valve (6) and second automatic cutout valve (7) all interlock with online moisture apparatus (5).

4. The gas-phase methanol fractional recovery process in a biodiesel acid-base two-step process according to claim 1, characterized in that: the methanol rectification system in the step (c) comprises a heater (11), a methanol rectification tower (12), a methanol tower top condenser (13), a reflux tank (14) and a tower bottom reboiler.

5. The gas-phase methanol fractional recovery process in a biodiesel acid-base two-step process according to claim 1, characterized in that: the methanol vaporizer (2) and the heater (11) are both indirect steam heat exchangers, and the first condenser (4) and the methanol tower top condenser (13) are both water-cooling heat exchangers.

6. The gas-phase methanol fractional recovery process in a biodiesel acid-base two-step process according to claim 1, characterized in that: the steps (a-d) may be performed simultaneously.

Technical Field

The invention relates to the technical field of gas-phase methanol recovery, in particular to a gas-phase methanol fractional recovery process in a biodiesel acid-base two-step method.

Background

In the biodiesel acid-base two-step process, a process route for reducing the acid value of raw oil by gas-phase methanol esterification is commonly adopted, and the flow of methanol is 0.5-1.2 m³The esterification reaction time is usually 4-6 h. The esterification reaction is characterized in that: the reaction rate is high within 1-2 h after the beginning of the reaction, the acid value is quickly reduced to below 10mgKOH/g, namely the water content of the recovered methanol is high, and the concentration of the methanol is continuously increased until the later stage is even up to 98%.

At present, the conventional operation is to completely collect the methanol in different reaction time periods and then feed the methanol into a rectifying tower for rectification, namely, the methanol with high later concentration enters the rectifying tower together with the methanol with low earlier concentration for rectification, and the methanol evaporation and the methanol rectification occupy higher energy consumption in the whole biodiesel production process, so that the methanol with high concentration is unnecessary for rectification, and the requirements on the processing capacity of the methanol rectifying system equipment are larger, the purchase cost is increased and the energy is wasted.

Therefore, it is necessary to provide a gas phase methanol fractional recovery process in a biodiesel acid-base two-step process to solve the above problems.

Disclosure of Invention

Technical problem to be solved

The invention aims to provide a gas-phase methanol fractional recovery process in a biodiesel acid-base two-step method, which aims to solve the problems of high investment and high energy consumption of gas-phase methanol recovery equipment in the existing biodiesel acid-base two-step method in the background art.

(II) technical scheme

In order to achieve the purpose, the invention is realized by the following technical scheme: a gas phase methanol fractional recovery process in a biodiesel acid-base two-step method comprises the following steps:

step a: condensing purge gas generated at a gas phase outlet of the esterification kettle through a first condenser;

step b: analyzing and determining the concentration of methanol in the condensate by an online moisture meter, and storing the condensate into a low-concentration methanol tank and a high-concentration methanol tank in a classified manner according to the concentration of the methanol in the condensate;

step c: sending the low-concentration methanol in the low-concentration methanol tank into a methanol rectification system for rectification, and conveying the rectified high-concentration methanol into a high-concentration methanol tank;

step d: introducing high-concentration methanol in the high-concentration methanol tank into a methanol gasifier for gasification, and then introducing the gasified methanol into an esterification kettle.

Further, the condensate in step b is obtained by condensing the purge gas in step a.

Further, the inlet of low concentration methyl alcohol jar is equipped with first automatic cutout valve, the inlet of high concentration methyl alcohol jar is equipped with second automatic cutout valve, first automatic cutout valve and second automatic cutout valve all interlock with online moisture apparatus.

Further, the methanol rectification system in the step comprises a heater, a methanol rectification tower, a methanol tower top condenser, a reflux tank and a tower bottom reboiler.

Further, the methanol gasifier and the heater are both indirect steam heat exchangers, and the first condenser and the methanol tower top condenser are both water-cooled heat exchangers.

Further, the steps (a-d) may be performed simultaneously.

(III) advantageous effects

Compared with the prior art, the invention provides a gas phase methanol grading recovery process in a biodiesel acid-base two-step method, which has the following beneficial effects:

according to the gas-phase methanol fractional recovery process in the biodiesel acid-base two-step method, the characteristic that esterification reaction is performed at first and then at last is utilized, an online moisture tester is arranged at a recovered methanol liquid outlet, concentration measurement is performed on esterified recovered methanol at different time nodes, fractional recovery is performed on methanol according to a measurement result, methanol with high water content in the early stage enters a methanol rectification system, and methanol with low water content in the later stage is directly recycled. On one hand, the treatment capacity of the methanol rectification system is reduced, so that the equipment specification of the methanol rectification system is reduced, and the investment is reduced; on the other hand, the 'repeated labor' is avoided, and the energy consumption of the methanol rectification is reduced.

Drawings

FIG. 1 is a schematic process flow diagram of the present invention.

In the figure: 2. a methanol vaporizer; 3. an esterification kettle; 4. a first condenser; 5. an online moisture meter; 6. a first automatic shut-off valve; 7. a second automatic shut-off valve; 8. a low concentration methanol tank; 9. a high concentration methanol tank; 11. a heater; 12. a methanol rectifying tower; 13. a methanol tower top condenser; 14. and (7) refluxing the tank.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments.

Referring to fig. 1, a gas phase methanol fractional recovery process in a biodiesel acid-base two-step process comprises the following steps:

step a: the purge gas generated at the gas phase outlet of the esterification kettle 33 is condensed by the first condenser 4, so that the gas phase methanol is condensed into liquid.

Step b: the concentration of the methanol in the condensate is analyzed and determined by an online moisture meter 5, the condensate in the step b is obtained by condensing the purge gas in the step a, and storing the condensate into a low-concentration methanol tank 8 and a high-concentration methanol tank 9 according to the concentration of methanol in the condensate in a classified manner, wherein a first automatic cut-off valve 6 is arranged at a liquid inlet of the low-concentration methanol tank 8, a second automatic cut-off valve 7 is arranged at a liquid inlet of the high-concentration methanol tank 9, the first automatic cut-off valve 6 and the second automatic cut-off valve 7 are interlocked with an online moisture tester 5, the online analysis of the methanol concentration in the gas-phase methanol condensate is carried out by an online moisture meter 5, according to the analysis result, the opening and closing of the first automatic cut-off valve 6 and the second automatic cut-off valve 7 are controlled, the low-concentration methanol solution and the high-concentration methanol solution are respectively sent into the low-concentration methanol tank 8 and the high-concentration methanol tank 9 for caching, and the concentration height judgment threshold value related to the methanol solution is determined according to the actual production requirement.

Step c: sending the low-concentration methanol in the low-concentration methanol tank 8 into a methanol rectifying system for rectification, wherein the methanol rectifying system comprises a heater 11, a methanol rectifying tower 12, a methanol tower top condenser 13, a reflux tank 14 and a tower bottom reboiler, heating the low-concentration methanol by the heater 11, sending the heated low-concentration methanol into the methanol rectifying tower 12 for rectification, condensing and extracting the high-concentration methanol from the top of the methanol rectifying tower 12 by the methanol tower top condenser 13, and sending the high-concentration methanol into the high-concentration methanol tank 9.

Step d: introducing the high-concentration methanol solution in the high-concentration methanol tank 9 into the methanol gasifier 2 for gasification, and then introducing the gasified solution into the esterification kettle 3 for recycling, wherein the steps (a-d) can be synchronously carried out.

The methanol gasifier 2 and the heater 11 are both indirect steam heat exchangers, the first condenser 4 and the methanol tower top condenser 13 are both water-cooled heat exchangers, and the processing capacity of the methanol rectification system is reduced by shunting methanol solutions with different concentrations, so that the diameter of the methanol rectification tower 12, the area of the methanol tower top condenser 13 and the area of a tower bottom reboiler can be reduced, the investment of the methanol rectification system is reduced, and meanwhile, the corresponding energy consumption is reduced.

Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.