阅读说明：本技术 一种节能环保秸秆制浆工艺 (Energy-saving environment-friendly straw pulping process ) 是由 张立平 于 2020-10-16 设计创作，主要内容包括：本发明公开了一种节能环保秸秆制浆工艺,包括以下步骤：步骤一、将秸秆原料破碎成5-10cm的小段,并使秸秆原料的含水量保持8％-22％；步骤二、对秸秆原料通入三氧化硫气体,反应条件为：所述三氧化硫气体与所述秸秆原料的质量比为1：200-1:2000,在封闭容器内保持无氧环境进行反应,反应温度为20-75℃,反应时间为20-60min,反应压力为正常大气压,生成纤维与糖类混合物；步骤三、对所述步骤二生成的纤维与糖类混合物利用冲洗介质进行冲洗,得到木质素、半纤维及纤维素固体；步骤四、对所述步骤三冲洗后获得的木质素、半纤维及纤维素固体进行研磨。本发明涉及造纸制浆领域,与现有技术相比的优点在于：能耗低、纤维提取率高、环境污染小、制浆质量好。(The invention discloses an energy-saving environment-friendly straw pulping process, which comprises the following steps: crushing straw raw materials into small sections of 5-10cm, and keeping the water content of the straw raw materials at 8% -22%; step two, introducing sulfur trioxide gas into the straw raw material, wherein the reaction conditions are as follows: the mass ratio of the sulfur trioxide gas to the straw raw material is 1: 200-1:2000, reacting in a closed container in an oxygen-free environment at 20-75 deg.C for 20-60min under normal atmospheric pressure to obtain a mixture of fiber and saccharide; washing the mixture of the fibers and the saccharides generated in the step two by using a washing medium to obtain lignin, hemicellulose and cellulose solids; and step four, grinding the lignin, the hemicellulose and the cellulose solid obtained after the washing in the step three. The invention relates to the field of papermaking and pulping, and compared with the prior art, the invention has the advantages that: low energy consumption, high fiber extraction rate, little environmental pollution and good pulping quality.)

1. An energy-saving environment-friendly straw pulping process is characterized by comprising the following steps:

crushing straw raw materials into small sections of 5-10cm, and keeping the water content of the straw raw materials at 8% -22%;

step two, introducing sulfur trioxide gas into the straw raw material, wherein the reaction conditions are as follows: the mass ratio of the sulfur trioxide gas to the straw raw material is 1: 200-1:2000, reacting in a closed container in an oxygen-free environment at 20-75 deg.C for 20-60min under normal atmospheric pressure to obtain a mixture of fiber and saccharide;

washing the mixture of the fibers and the saccharides generated in the step two by using a washing medium to obtain lignin, hemicellulose and cellulose solids;

and step four, grinding the lignin, the hemicellulose and the cellulose solid obtained after the washing in the step three.

2. The energy-saving environment-friendly straw pulping process according to claim 1, characterized in that: and the concentration of sulfur trioxide molecules in the sulfur trioxide gas in the second step is more than or equal to 98 percent.

3. The energy-saving environment-friendly straw pulping process according to claim 1, characterized in that: and the flushing medium in the third step is water, ammonia water, a sodium hydroxide solution or a potassium hydroxide solution.

4. The energy-saving environment-friendly straw pulping process according to claim 1, characterized in that: the straw raw materials comprise rice straw, corn straw, reed and bagasse.

Technical Field

The invention relates to the field of papermaking and pulping, in particular to an energy-saving and environment-friendly straw pulping process.

Background

China is the country with the largest paper and paperboard yield and consumption in the world, but fiber raw materials used for papermaking have large gaps and are always seriously dependent on import, and the outward dependence of the papermaking raw materials (wood pulp, waste paper and wood chips) in China is as high as more than 50 percent. With the orderly promotion of the 'transformation scheme for forbidding foreign garbage to promote solid waste import management system', zero import of waste paper is basically realized by the end of 2020, and compared with 2017, the gap of the papermaking fiber raw material with more than 2000 million tons exists. However, China is a big agricultural country, crop straws are various in types, large in quantity and wide in distribution, about 20% of the agricultural straws cannot be utilized at present, and the straws can be used as fiber sources of paper pulp.

At present, straw pulping methods comprise the following steps: in the traditional chemical pulping, particularly alkaline pulping, the straws are soaked, lignin and fibers in the straws are mixed and extracted into wood pulp black liquor, and the wood pulp black liquor is ground and pulped, but the waste water, waste gas and waste residue generated in the pulping and papermaking production process have great influence on the environment, wherein the influence of the waste water discharge on the environment is particularly serious; the mechanical pulping method is characterized in that raw materials are heated by high-temperature steam and are ground by a mechanical device to produce usable paper pulp, but the method has huge energy consumption and poor economic benefit; the enzyme treatment method is characterized in that the straws are treated by specific enzymes, and the method has high requirements on reaction temperature control accuracy, long reaction time and high cost, and is not suitable for industrial production.

Chinese patent publication No. CN1015385967A, published in 2019, 4 and 22, and entitled "method for treating straws with sulfur trioxide", discloses a method for treating straws with sulfur trioxide, and uses sulfur trioxide gas and dilute alkali liquor to treat straws so as to separate obtained lignocellulose, and uses cellulase to saccharify the lignocellulose so as to obtain saccharified liquid. The scheme can separate the fibers in the straw raw materials to obtain polysaccharide, lignin and cellulose, but in the field of papermaking and pulping, the fibers (lignin, cellulose, semi-fibers, crude fibers and the like) are mainly used for pulping, and although the scheme of the invention can simply pretreat the fibers, the problems of too long flow, low conversion efficiency, poor pulp yield and the like can occur if the scheme is applied to the field of pulping due to the lack of necessary links and processes for efficiently separating the cellulose, so that the fiber impurity is more, the quality of the final paper finished product is poorer, and the scheme is not suitable for straw pulping.

Disclosure of Invention

The invention aims to solve the technical problems and provide an energy-saving environment-friendly straw pulping process which is low in energy consumption, high in fiber extraction rate, low in environmental pollution and good in pulping quality.

In order to achieve the purpose, the invention adopts the technical scheme that: the energy-saving environment-friendly straw pulping process comprises the following steps:

crushing straw raw materials into small sections of 5-10cm, and keeping the water content of the straw raw materials at 8% -22%; the water content of the straw harvesting raw material is about 15%, the water content of the straw raw material is kept in a specific interval, the heat release and acid substance generation reaction of water and sulfur trioxide are facilitated, too little water content cannot react or the reaction rate is slow, and too much water content can prevent the straw raw material from being completely decomposed.

Step two, introducing sulfur trioxide into the straw raw material, wherein the reaction conditions are as follows: the mass ratio of the sulfur trioxide to the straw raw material is 1: 200-1:2000, and reacting in a closed container in an oxygen-free environment at 20-75 deg.C for 20-60min under normal atmospheric pressure to obtain a mixture of fiber and saccharide. The method can effectively utilize the chemical combination reaction of sulfur trioxide and water in the straw raw material in a closed oxygen-free environment so as to obtain instantaneous high temperature and generate sulfuric acid or sulfurous acid, and the binding force between the hemicellulose and the lignin in the straw is reduced by utilizing acidity and high temperature. While the fibrous substances are in a solid state, the other substances such as saccharides are dissolved in the mixed liquid remaining from the reaction. The reaction can only be kept at normal temperature because of the heat release of the chemical reaction, and the reaction rate is higher because the reaction environment is closed and oxygen-free.

The mixture of fiber and saccharide obtained by the process mainly comprises saccharide substances, xylose, pentose, other monosaccharide and little lignin. There are three main ways to utilize the above liquid substances: producing an animal feed additive; extracting xylose or xylo-oligosaccharide; converting xylitol or furfural; producing the methane. The waste water produced in the production process can be recycled, thereby realizing zero discharge of water.

Washing the mixture of the fibers and the saccharides generated in the step two by using a washing medium to obtain lignin, hemicellulose and cellulose solids;

and step four, grinding the lignin, the hemicellulose and the cellulose solid obtained after the washing in the step three.

Further, the sulfur trioxide molecular concentration in the sulfur trioxide gas in the second step is more than or equal to 98%. The commonly used sulfur trioxide gas in industrial production is sulfur trioxide gas with the concentration more than 98 percent, and the sulfur trioxide gas with higher concentration can accelerate the reaction speed.

Further, the flushing medium in the third step is water, ammonia water, a sodium hydroxide solution or a potassium hydroxide solution. And (3) in the flushing process, the waste liquid generated in the step three can be neutralized by using alkaline substances, and the waste water does not need to be subjected to separate post-treatment.

Further, the straw feedstock includes rice straw, corn stover, reed and bagasse.

Compared with the prior art, the process has the advantages that: the sulfur trioxide is used for generating an acid environment and instantaneous high heat when meeting water, so that the binding force between the half fiber and the lignin in the straw is reduced, the half fiber and the lignin are separated, a sealed and oxygen-free reaction environment is adopted, the straw can be decomposed at normal temperature and normal pressure, and the process is low in energy consumption because additional heating is not needed; the process can convert 95 percent of fiber in the straw, the strength performance of the obtained paper pulp is obviously better than that of domestic waste paper recycled paper pulp, particularly the ring crush strength is higher, the process is suitable for manufacturing packaging materials such as corrugated base paper, box board and the like, and the quality of a papermaking finished product is higher; the system uses less water, and the generated water liquid has high added value, so the system is more environment-friendly; as the pulping raw material only needs straw and sulfur trioxide gas, the treatment cost is lower, and the economic benefit is better.

Detailed Description

The following description is only a preferred embodiment of the present invention, and does not limit the scope of the present invention, and the present invention will be further described with reference to the following embodiments.

Example 1, 10kg of wheat straw is crushed into 5cm small sections by a vertical crusher, preliminary dust removal is carried out by a dust removal screen, rubbing and grinding are carried out by a rubbing and grinding machine, the wheat straw is placed into a closed reaction tank, 0.05kg of sulfur trioxide gas is introduced, reaction is carried out in an oxygen-free environment, the reaction temperature is 20 ℃, the reaction time is 40min, and the reaction pressure is normal atmospheric pressure, so that a fiber mixture is generated; and carrying out spiral washing on the generated fiber mixture, separating to obtain lignin, hemicellulose and cellulose mixed solid, dehydrating by using a dehydrator, and grinding by using a refiner to obtain 8.1kg of papermaking raw pulp.

Example 2, 10kg of wheat straw is crushed into 5cm small sections by a vertical crusher, preliminary dust removal is carried out by a dust removal screen, rubbing and grinding are carried out by a rubbing and grinding machine, the wheat straw is placed into a closed reaction tank, 0.06kg of sulfur trioxide gas is introduced, reaction is carried out in an oxygen-free environment, the reaction temperature is 20 ℃, the reaction time is 40min, and the reaction pressure is normal atmospheric pressure, so that a fiber mixture is generated; and (3) carrying out spiral washing on the generated fiber mixture, separating to obtain lignin, hemicellulose and cellulose mixed solid, dehydrating by using a dehydrator, and grinding by using a refiner to obtain 7.8kg of papermaking raw pulp.

Example 3, 10kg of wheat straw is crushed into 5cm small sections by a vertical crusher, preliminary dust removal is carried out by a dust removal screen, rubbing and grinding are carried out by a rubbing and grinding machine, the wheat straw is placed into a closed reaction tank, 0.08kg of sulfur trioxide gas is introduced, reaction is carried out in an oxygen-free environment, the reaction temperature is 20 ℃, the reaction time is 40min, and the reaction pressure is normal atmospheric pressure, so that a fiber mixture is generated; and (3) carrying out spiral washing on the generated fiber mixture, separating to obtain lignin, hemicellulose and cellulose mixed solid, dehydrating by using a dehydrator, and grinding by using a refiner to obtain 7.2kg of papermaking raw pulp.

The properties of the pulp produced by the above process are shown in table 1:

TABLE 1 Properties of the pulps obtained by the process

The invention and its embodiments have been described above without limitation to such description, and the actual structure is not limited to this. In summary, those skilled in the art should appreciate that they can readily use the disclosed conception and specific embodiments as a basis for designing or modifying other structures for carrying out the same purposes of the present invention without departing from the spirit and scope of the invention as defined by the appended claims.