CN106942471B

CN106942471B - Method for preparing feed by treating bean dregs through hydrothermal carbonization

Info

Publication number: CN106942471B
Application number: CN201710216212.7A
Authority: CN
Inventors: 张镭; 高玉军; 王建宏; 周业剑; 唐军义; 施耐德克劳迪娅; 马克布特曼
Original assignee: Beijing Shunhong Jinjian Environment Technology Development Co ltd
Current assignee: Beijing Shunhong Jinjian Environment Technology Development Co ltd
Priority date: 2017-04-05
Filing date: 2017-04-05
Publication date: 2021-04-27
Anticipated expiration: 2037-04-05
Also published as: CN106942471A

Abstract

The invention provides a method for preparing feed by treating bean dregs through hydrothermal carbonization, which is characterized in that two acid catalysts are added in two steps, namely, citric acid is added before entering a reactor, and acetic acid is added into the reactor in the midway of the reaction.

Description

Method for preparing feed by treating bean dregs through hydrothermal carbonization

Technical Field

The invention relates to the field of soybean protein production and pollutant treatment, and provides a method for preparing feed by treating bean dregs through hydrothermal carbonization.

Background

The soybean protein is generally protein derived from soybean, has amino acid composition similar to that of milk, does not contain cholesterol, contains peculiar active ingredients such as isoflavone and the like, and has high nutritional value. Because the soybean protein has the advantages, the preparation raw materials are low in cost and easy to obtain, the preparation technology is relatively simple, the development of the domestic soybean protein preparation industry is rapid, and the number of domestic large soybean protein production enterprises is nearly hundreds and medium-sized enterprises is more by 2015.

The basic process of the soybean protein production of domestic enterprises at present is as follows: low temperature leaching-alkali dissolution-acid precipitation-centrifugation-spray drying or enzyme treatment, wherein a large amount of bean dregs (about 5 tons of bean dregs per ton of protein) are generated after alkali dissolution, and a large amount of waste water (about 20 tons of waste water with high COD and BOD per ton of protein) is generated after acid precipitation and centrifugation. If not properly disposed of, it can cause serious pollution problems, and if not fully utilized, it can be a significant waste of resources.

At present, the main direction of the bean dregs is to feed factories, and the wastewater is mainly treated by sewage factories. Because the bean dregs have high water content and are extremely easy to rot, and the bean dregs contain trypsin inhibitor which is easy to cause pig diarrhea and are directly used as feed or inconvenient to process, the bean dregs can be directly used as fertilizer or even discarded in many times. Sludge generated by the precipitation of the wastewater for producing the soybean protein, namely the bean dreg black mud, has the problems of large occupied area, pollution and the like no matter in composting and landfill. The ideal state of reduction, harmlessness, stabilization and recycling of the comprehensive treatment and utilization distance of the waste produced in the production process of the soybean protein has a great difference.

Disclosure of Invention

The applicant further optimizes the hydrothermal carbonization treatment process and tries to expand the application range thereof on the basis of introducing German Buttmann hydrothermal carbonization treatment technology to construct equipment and actually operating and treating sludge (Beijing, Yanzhou, Jining and the like) of urban domestic sewage plants. In experiments, the applicant finds that the hydrothermal carbonization technology can be completely used for treating the bean dregs and the bean dregs black mud, can effectively reduce the water content of the bean dregs and the bean dregs black mud, and can improve the nutrient element composition of the bean dregs and the black mud. The existing hydrothermal carbonization catalyst type and adding mode (concentrated sulfuric acid is added once before entering a reactor) are changed into two times of stepwise addition (citric acid is added before entering the reactor, and acetic acid is added into the reactor in the midway of the reaction), so that the water content of the product can be better improved to realize better reduction/preservation effect. Meanwhile, the activity of the trypsin inhibitor can be effectively eliminated by high-temperature treatment, strong acid which possibly has safety problems is not used in the treatment process (a small amount of acid which is not fully mixed with other components can be reserved in a cavity generated by local mud), and the bean dregs treatment product can be directly used as feed.

The bean dregs in the invention refer to solid waste generated after raw soybeans are processed in the production of soybean protein or other deep processing processes of soybeans.

On the one hand, the method for preparing the feed by treating the bean dregs through hydrothermal carbonization comprises the following steps:

a. collecting bean dregs;

b. sending the bean dregs to a reactor, and adding citric acid in the reactor;

c. carrying out hydrothermal carbonization reaction in a reactor, and adding acetic acid during the hydrothermal carbonization reaction;

d. collecting the produced biological carbon slurry;

e. pressing to dewater, pulverizing, and bagging to obtain feed.

In a further aspect, the citric acid used in the method is solid citric acid and the acetic acid is glacial acetic acid.

In a further aspect, citric acid is added in an amount of 1-2% (w/v) and acetic acid is added in an amount of 1-2% (v/v).

In a further aspect, citric acid is added in an amount of 2% (w/v) and acetic acid is added in an amount of 1.5% (v/v) used in the method.

In a further aspect, the hydrothermal carbonization temperature is 150-.

In a further aspect, the hydrothermal carbonization temperature is 150 ℃, the pressure is 15bar, and the time is 120 minutes.

In a further aspect, the hydrothermal carbonization is carried out by adding acetic acid until one-fourth of the expected reaction time.

And in the step d, the generated biological carbon slurry is collected through a pressure relief system under the condition of ensuring the operation pressure of the system, the heat of the biological carbon slurry is received through a heat exchange system in the period, the obtained heat is used for preheating the bean dregs in the step b through a front heat exchange system, and the carbon slurry is depressurized through a pressure relief system and then is delivered to a buffer storage tank under residual pressure.

In a further aspect, the pressure in the reactor is provided by a pump that delivers the okara.

Drawings

FIG. 1 is a complete process flow diagram of the hot water carbonization treatment technology of bean dregs. In the figure: 1. feed hopper, 2, the force (forcing) pump, 3, preceding heat exchanger system, 4, heat recovery, 5, 1# catalyst throw with some, 6, the reactor, 7, back heat exchanger system, 8, the release system, 9, the carbon thick liquid storage storehouse, 10, sheet frame dewatering device, 11, waste water treatment (option), 12, 1# catalyst throw with the pump, 13, 2# catalyst throw with the pump, 14, the biological charcoal heat conduction oil furnace, 15, the filtrating storage tank, 16, the feed bin, A, the bean dregs of moisture content 75%, B, precipitate repayment (optional), C, the water return mill water inlet after handling, D, biological charcoal cake.

FIG. 2 is an external view of an apparatus (3000 ton year capacity) used by the applicant for actually treating okara.

Detailed Description

Example 1 treatment of okara

The bean dreg sample source is as follows: the bean dregs produced by Shandong Xingshi Soybean biological Limited company have the water content of about 80 percent.

The treatment process of the invention comprises the following steps:

a. collecting bean dregs by using a closed spiral;

b. feeding the okara to a reactor, during which 2% (w/v) citric acid is added and the okara is preheated by a previous heat exchange system;

c. carrying out hydrothermal carbonization reaction in a reactor, wherein the hydrothermal carbonization temperature is 150 ℃, the pressure is 15bar, the time is 120 minutes, 1.5% (v/v) of glacial acetic acid is added when the reaction is carried out for about 30 minutes, and the pressure in the reactor is provided by a pump for conveying bean dregs;

d. collecting the generated biological carbon slurry by a pressure relief system under the condition of ensuring the operating pressure of the system, and cooling and recovering heat by a post heat exchange system in the period;

e. pressing to dewater, pulverizing, and bagging to obtain feed.

Control treatment procedure 1:

the basic treatment process is the same as the treatment process of the invention, wherein no acid catalyst is added, and the hydrothermal carbonization temperature is adjusted to 180 ℃, the pressure is adjusted to 20bar, and the time is adjusted to 150 minutes.

Control treatment procedure 2:

the basic process is the same as the process of the present invention, wherein only 1.5% of 98% concentrated sulfuric acid is added as a single catalyst in step b.

Control treatment procedure 3:

the basic treatment process is the same as the treatment process of the invention, wherein only 1.5 percent of 98 percent concentrated sulfuric acid is added as a single catalyst in the step b, and the hydrothermal carbonization temperature is adjusted to 180 ℃, the pressure is adjusted to 20bar, and the time is adjusted to 150 minutes.

The above treatment was carried out using the same equipment and the same feed amount of okara (1.5 tons).

Example 2 comparison of the effects of the treatment methods in example 1

Measuring the water content, protein content (Kjeldahl method) and fat content (Soxhlet extraction method) of the obtained charcoal cake

The result shows that compared with the existing hydrothermal carbonization method, the method can more effectively reduce the moisture content of the bean dregs so as to better realize decrement, and simultaneously prolong the preservation time (the data is shown in example 3); shortening the reaction time (better than controls 1 and 3, which have longer reaction times); the protein content in the product is effectively improved, so that the feed quality is improved (even if the difference of the water content is eliminated, the protein content of the product of the method is obviously higher than that of the contrast, which is probably caused by a better wall breaking and decomposing process generated by adding two acids step by step); the method of the invention has no obvious difference from the prior hydrothermal carbonization treatment technology in construction and operation cost (the acetic acid and the citric acid are low in price and safer to operate and store than concentrated sulfuric acid).

Example 3 actual feed preparation and use

The bean dregs obtained by plate pressing dehydration have low water content and are suitable for transportation and storage for a certain time. The original bean dregs can be fermented to generate extremely unpleasant smell after being stacked in the open air for about 2 days, the operator is difficult to access without protection, and obvious putrefactive smell can be generated after the treated carbon cakes are stacked in the open air for 15 days.

The bean dreg feed is used for feeding about 100 pigs in 2 batches at the adding amount of 20 percent, and farmers react that the growth condition of the pigs is normal and the occurrence of the crowd diarrhea obviously related to the bean dregs does not occur.

The bean dreg feed produced by the invention can be further fermented and processed after being mixed with bran and the like, and is used for livestock and poultry such as laying hens and the like.

Claims

1. A method for preparing feed by treating bean dregs through hydrothermal carbonization is characterized by comprising the following steps:

a. collecting bean dregs;

b. sending the bean dregs to a reactor, and adding citric acid in the reactor;

d. collecting the produced biological carbon slurry;

e. pressing to dewater, crushing and bagging to obtain feed;

wherein the citric acid is solid citric acid, and the acetic acid is glacial acetic acid; the addition of citric acid is 2% w/v and the addition of acetic acid is 1.5% v/v; the hydrothermal carbonization temperature is 150 ℃, the pressure is 15bar, and the time is 120 minutes; acetic acid was added when hydrothermal carbonization proceeded for 30 minutes.

2. The method according to claim 1, wherein the generated biochar slurry is collected by a pressure relief system under the condition of ensuring the operating pressure of the system in the step d, heat of the biochar slurry is received by a heat exchange system during the period, the obtained heat is used for preheating the bean dregs in the step b by a front heat exchange system, and the carbon slurry is depressurized by a pressure relief system and then is delivered to a buffer storage tank under the residual pressure.

3. A process according to claim 1 or 2, wherein the pressure in the reactor is provided by a pump for transporting the okara.