CN-114350389-B - Water plant high-value recycling process

CN114350389BCN 114350389 BCN114350389 BCN 114350389BCN-114350389-B

Abstract

The application discloses a water plant high-value recycling process, which comprises four processes of deep dehydration, pyrolysis gasification, product purification and collection and product quality improvement of water plants. The method comprises the following steps of placing salvaged aquatic weeds for 24-48 hours, cutting up, carrying out deep dehydration by using a dehydrating agent, separating and recycling the dehydrating agent, sending the obtained solid product into an anaerobic or low-oxygen rotary kiln for continuous pyrolysis and gasification, condensing, separating, purifying and drying the obtained gas to obtain synthesis gas and biological oil respectively, collecting the obtained solid to obtain biological carbon, and carrying out quality improvement treatment on the obtained product according to actual requirements, thereby realizing high-value recycling of the aquatic weeds and avoiding secondary pollution.

Inventors

CAO JUN
ZHU WEI
SUN JIPENG
LIN NAIXI

Assignees

河海大学

Dates

Publication Date: 20260505
Application Date: 20210914

Claims (8)

1. A process for recycling aquatic weeds in a high-value mode is characterized by comprising four steps of deep dewatering of aquatic weeds, pyrolysis gasification, purification and collection of products and quality improvement of the products, wherein salvaged aquatic weeds are placed for 24-48 hours and then cut up, deep dewatering is carried out by using a dehydrating agent, the dehydrating agent is separated and recycled, the obtained solid products are sent into an anaerobic or low-oxygen rotary kiln for continuous gasification pyrolysis, the obtained gases are condensed, separated, purified and dried to obtain synthetic gas and biological oil respectively, the obtained solids are collected to obtain biological carbon, quality improvement treatment is carried out on the obtained products according to actual requirements, high-value recycling of the aquatic weeds is achieved, secondary pollution is avoided, and the method specifically comprises the following steps: Firstly, naturally placing salvaged aquatic weed for 24-48 hours, reducing the water content of the aquatic weed to 70-85%, then cutting the aquatic weed to 1-5cm, fully stirring the prepared dehydrating agent and the pretreated aquatic weed in a container with the pressure of 0.1-0.8MPa for 40-60 minutes at the speed of 100-500 r/min, stopping stirring when the water content of the aquatic weed is reduced to 5-15%, boosting to normal pressure, recycling the dehydrating agent with the water content of more than 80%, separating liquid from solid, and enabling the aquatic weed subjected to solid deep dehydration to enter a second step; Introducing N 2 into a closed rotary kiln, discharging >95% of air in the rotary kiln to realize an anaerobic or low-oxygen state, setting the reaction temperature to 300-600 ℃ according to the product requirement, enabling the water plants after solid deep dehydration to enter the rotary kiln through a screw feeder to carry out pyrolysis gasification after the reaction temperature is reached, and controlling the feeding amount through the screw feeder, wherein the time of the pyrolysis gasification of the water plants is 10-30 min, and the water plants are used in the third step; Condensing, separating, purifying and drying pyrolysis gas generated by pyrolysis and gasification to respectively obtain synthesis gas and biological oil, and collecting solids to obtain biochar for the fourth step; The fourth step, the product synthesis gas, biological oil and biological carbon are obtained to be directly used or upgraded according to the actual application requirement, the synthesis gas is used in the preheated gas of a rotary kiln, or is connected into a resident civil gas pipe network through deep purification, or is further cracked and reformed to obtain a chemical product with higher quality, the biological oil is upgraded to be used as biodiesel and ethanol through further adding a catalyst, and the biological carbon is used as a soil improver, is used as an adsorbent to adsorb heavy metal pollutants and is used as fuel to further upgrade the commercial activated carbon partially or completely according to the property of the biological oil; And fifthly, the biochar of the aquatic weeds is directly applied to a river and lake bank dike protection material, heavy metal pollutants in rainwater and industrial and agricultural sewage are filtered, adsorbed and purified, and meanwhile, the biochar is favorable for plant growth of the dike protection due to water absorption and rich nitrogen and phosphorus content, and is favorable for realizing ecological dike protection.
2. The process for recycling aquatic weeds at high value according to claim 1, wherein the dehydrating agent in the first step is prepared by fully mixing 80-95% of active components and 5-15% of auxiliary components under the pressure of 0.1-0.8 MPa.
3. The process for recycling aquatic weeds with high value according to claim 2, wherein the active component is L-DME, and separation and recovery can be realized after dehydration is completed.
4. The process for recycling aquatic weeds with high value according to claim 2, wherein the auxiliary agent component is enzyme.
5. The process for recycling aquatic weeds according to claim 4, wherein the enzyme is a lyase.
6. The process for recycling aquatic weeds according to claim 5, wherein the lyase is cellulase and/or pectase.
7. The process for recycling aquatic weeds at high value according to claim 1, wherein the pyrolysis gasification reaction furnace in the second step is a closed rotary kiln, the rotary kiln adapts to the heterogeneity of the aquatic weeds, the clamping and the blocking are avoided, the uniform pyrolysis gasification of the aquatic weeds is realized, the feeding rate of the aquatic weeds is timely adjusted by a screw feeder according to the running condition of the reactor, and the sealing effect is achieved.
8. The process for recycling aquatic plants according to claim 1, wherein the synthetic gas, the biological oil and the biological carbon in the third step are subjected to reaction temperature adjustment according to requirements, products with different mass ratios are obtained in the reaction furnace and the oxygen content, and the products are condensed, separated, purified and dried.

Description

Water plant high-value recycling process Technical Field The invention belongs to the field of ecological water conservancy and renewable energy sources, in particular to a process for recycling water plants with high value, the process for treating aquatic weeds (water hyacinth, water peanut, water lettuce and the like) in rivers and lakes is suitable for high-value resource utilization of biomass with different water contents and nonuniform raw materials. Background Along with the expansion of the urban construction scale and the rapid development of economy, river and lake pollution is more and more serious, a large amount of untreated or not-effectively treated biological sewage and industrial and agricultural production wastewater are discharged into rivers, lakes and oceans, the eutrophication of water bodies is aggravated, the aquatic weeds are overgrown, the ecological balance of the water bodies is destroyed, and serious ecological environment problems are brought. In the face of this increasingly prominent environmental problem, physical salvaging of aquatic weeds floating on the surface of a body of water is a major approach to solving the problem. How to treat the salvaged aquatic plants is an important problem facing river and lake management. In spring, summer and autumn each year, the daily salvage amount of the water grass is huge and is up to millions of tons, and the salvaged water grass is dumped to a landfill site, a gully or a water side depression, is easy to rot and produce peculiar smell after long-time stacking, and is easy to produce secondary pollution after scouring of rainwater. However, due to the characteristics of high water content, high organic matter content, easy decay, heavy metal content and the like of the aquatic weeds, how to fully recycle the aquatic weeds on the basis of avoiding secondary pollution changes wastes into valuables is a current challenge. In particular, since the water content of the aquatic weeds is high, whatever treatment method is used, the aquatic weeds are dehydrated, but since most of the water of the aquatic weeds is water combined with organic matters, the dehydration is difficult, and the dehydration technology has a certain problem, so that means for subsequent recycling are limited. And at present, the treatment of aquatic weeds lacks a large-scale process flow, so the patent aims to provide a method for realizing reasonable and efficient recycling treatment of aquatic weeds, avoiding secondary pollution and realizing full utilization of resources. Disclosure of Invention The application mainly provides a water plant high-value recycling process, solves the technical problems of huge water plant salvage amount, high water content, difficult dehydration, difficult treatment and disposal and low resource utilization rate in the prior art, and discloses a process comprising four processes of deep dehydration, gasification pyrolysis, product purification and collection and product quality improvement of water plants. Placing salvaged aquatic weeds for 24-48 hours, cutting, deep dehydrating by using a dehydrating agent, separating and recycling the dehydrating agent, sending the obtained solid product into an anaerobic or low-oxygen rotary kiln for continuous gasification pyrolysis, condensing, separating, purifying and drying the obtained gas to obtain synthesis gas and bio-oil respectively, collecting the obtained solid to obtain biochar, and carrying out quality improvement treatment on the obtained product according to actual requirements, thereby realizing high-value recycling of the aquatic weeds and avoiding secondary pollution. The technical scheme includes that the process comprises four processes of deep dehydration, pyrolysis gasification, product purification and collection and product upgrading of aquatic weeds, salvaged aquatic weeds are placed for 24-48 hours and then cut up, deep dehydration is carried out by using a dehydrating agent, the dehydrating agent is separated and recycled, obtained solid products are sent into an anaerobic or low-oxygen rotary kiln to be continuously gasified and pyrolyzed, obtained gases are condensed, separated, purified and dried to obtain synthetic gas and biological oil respectively, obtained solids are collected to obtain biological carbon, and the obtained products are upgraded according to actual requirements, so that the high-value recycling of the aquatic weeds is realized, secondary pollution is avoided, and the method comprises the following steps: Firstly, naturally placing salvaged aquatic weed for 24-48 hours, reducing the water content of the aquatic weed to 70-85%, then cutting the aquatic weed to 1-5cm, fully stirring the prepared dehydrating agent and the pretreated aquatic weed in a container with the pressure of 0.1-0.8MPa for 40-60 minutes at the speed of 100-500 r/min, stopping stirring when the water content of the aquatic weed is reduced to 5-15%, boosting to normal pressure,