CN101768473A - Biomass and high heating value garbage gasifying method for distribution type renewable energy system - Google Patents

Abstract

The biomass and high calorific value waste gasification method of the distributed renewable energy system, in order to solve the low calorific value of the biomass gasification gas, cannot meet the fuel calorific value of the micro gas turbine in the distributed energy supply system, and the gasification process produces There is a lot of tar in the gas, which makes it difficult to purify the gas and affects the normal operation of the gas turbine. Take high calorific value gas. Breaking through the traditional conventional method of individual biomass gasification, through the chemical reaction process in the fluidized bed, the distributed renewable energy system has achieved the goals of high calorific value of gas, low environmental pollution, and stable gasification reaction. This method makes up for the shortcomings of non-renewable and insufficient raw materials in traditional distributed energy supply systems, meets the needs of gas turbines in distributed energy supply systems, and can significantly improve the utilization efficiency of renewable energy, and the raw materials are rich in sources and low in cost. At the same time, it solves the problem of partial treatment and disposal of urban white pollution and domestic garbage.

Description

Biomass and high calorific value waste gasification method for distributed renewable energy system

technical field

The invention relates to a gasification method of distributed renewable energy, in particular to a gasification method of biomass and high calorific value garbage in a distributed renewable energy system, and belongs to the technical field of renewable clean energy and the technology of producing fuel from waste field.

Background technique

The gasification method of distributed renewable energy is very promising for energy supply systems, and it is gradually being accepted by people because of its advantages of flexible adjustability, high energy utilization rate and low pollution. Conventional distributed energy supply systems use non-renewable natural gas as raw material, and my country's output is not high. Therefore, the use of renewable energy-based fuels has certain economic and environmental benefits. Biomass is a kind of renewable energy. The annual output of straw biomass in my country exceeds 600 million tons, but for a long time most of the crop straw has been burned in the field. This method not only has low biomass utilization efficiency, but also pollutes the air environment and is easy to cause fires and traffic accidents. According to the "Straw Straw Burning Prohibition and Comprehensive Utilization Management Measures" (Huanfa [1999] No. 98) promulgated by the State Environmental Protection Administration of my country, the burning of crop straws is prohibited in the burning-free zone.

The key to the early fuel supply of distributed renewable energy systems is to seek a technology to generate high calorific value gas. Biomass gasification is one of the most practical technologies in the thermochemical conversion of biomass. Biomass gasification refers to the process of converting solid biomass into combustible gases such as CO, H ₂ and CH ₄ by using oxygen or oxygen-containing substances in the air as gasification agents under incomplete combustion conditions. However, the calorific value of biomass gas obtained by gasification is low (4-6MJ/m ³ ), which is far from meeting the fuel calorific value of micro gas turbines in distributed energy supply systems, and the tar produced during the gasification process More, resulting in difficulty in gas purification, affecting the normal operation of the gas turbine.

The high calorific value garbage that the present invention adopts comprises waste plastics and domestic garbage through one-time crushing, garbage sorting and rejecting combustibles and kitchen waste, combustible paper, plastic rubber, wood bamboo and textiles (the proportion is 5% respectively. , 10%, 2% and 7%). After analysis, it is found that the gas calorific value of this high calorific value garbage gasification can reach as high as 12-35MJ/m ³ . my country's white garbage (waste plastic) accounts for an increasing proportion. According to statistics, in 2005, the domestic waste plastic production was about 9.608 million tons, and the discharge rate was about 36%, accounting for about 15% of my country's total garbage discharge (national Focus on waste plastic and rubber utilization technology. Renewable resources and circular economy, 2008(05)). Moreover, the amount of garbage accumulated in my country over the years is about 6 billion tons, and the output of urban domestic garbage is increasing rapidly at an average annual growth rate of about 9%. The huge reserves of domestic garbage have posed a serious threat to the ecological environment of the city and its surroundings. According to relevant regulations, fuels with gas production calorific value greater than 15.07MJ/ ^m3 are high calorific value fuels. Therefore, if these wastes with high calorific value are mixed into biomass, waste plastics and domestic waste can be processed and the calorific value of gas can be increased, which is in line with relevant national industrial policies and achieves the goal of energy conservation and environmental protection. Therefore, the fuel used in this "distributed renewable energy system" is a mixture of straw and waste with high calorific value.

According to relevant calculations, the application of combined gasification of biomass and high-calorific value waste can increase the comprehensive energy utilization rate of the distributed renewable energy system by 30-50% compared with the traditional power generation system, and the unit electricity price is 0.19% lower than the grid electricity price Yuan/KWh, the heating cost is 7.41 Yuan/m ² lower than central heating, which has certain economic advantages.

Contents of the invention

The invention uses biomass and high calorific value garbage as raw materials to generate gasification gas to meet the needs of gas turbines in distributed energy systems, and this invention makes up for the defects of non-renewable and insufficient raw materials in traditional distributed energy supply systems.

Biomass is a kind of renewable energy, but the calorific value of gas produced by biomass gasification is relatively low (4-6MJ/m ³ ), which cannot meet the fuel calorific value of micro gas turbines in distributed energy supply systems, and the gasification process More tar is produced, which makes gas purification difficult and affects the normal operation of the gas turbine. The biomass and high-calorific-value garbage gasification method adopted in the distributed renewable energy system of the present invention is a method that can meet the requirements of the distributed renewable energy system. The combined gasification method of biomass and high-calorific-value garbage with micro-turbine fuel calorific value can realize the subsequent combined supply of cold, heat and electricity in the system. This method uses a new type of porous bed material circulating fluidized bed gasifier to produce high-calorific value gas. Its preparation steps include:

(1) Put biomass and high calorific value waste into the furnace body with an operating temperature of 600-900°C at a mass ratio of 1:2, the fluidization velocity is greater than 3-5 times the particle terminal velocity, and the equivalent ratio is between 0.2- Between 0.25, biomass and high-calorific-value waste first undergo rapid decomposition to produce gas, coke and tar;

(2) Tar continues to be cracked in a high-temperature environment, while coke is further reduced with CO ₂ and H ₂ O, and the incompletely reacted carbon particles and gas are separated at the outlet, and the gas is sent away as a product through a gas collection device; coke The air is pumped back to the bottom of the fluidized bed 3 for combustion with the air, and the heat generated is supplied to the entire gasification furnace through the steam generator to ensure the endothermic process of pyrolysis and reduction, which basically meets the requirements of reduction and tar cracking;

(3) The residence time of the gas phase in the furnace is between 2-4s, and the residence time of the solid phase in the furnace can reach between 4-6s.

Compared with the prior art, the present invention has the following advantages:

1. Biomass and waste with high calorific value are selected as gasification raw materials, the gas produced has high calorific value, less environmental pollution, and comprehensive utilization of waste is realized;

2. The porous bed material is used instead of the ordinary bed material. The bed material has a strong promotion effect on the generation of H ₂ . Under the same conditions, the volume fraction of H ₂ can increase by up to 31.76%, which greatly improves the stability of the gas.

3. Biomass and waste with high calorific value are selected as gasification raw materials, which can meet the demand of micro gas turbine fuel calorific value in the distributed renewable energy system, and provide a guarantee for the distributed renewable energy system to realize the subsequent triple supply of cooling, heating and power.

It can be seen that the present invention uses biomass (straw) and high calorific value garbage (mainly waste plastics) to produce combustible gas, which breaks through the traditional conventional method of biomass gasification alone. The reaction process realizes the advantages of high calorific value of gas, less environmental pollution, and stable gasification reaction.

This method can significantly improve the utilization efficiency of renewable energy, and the source of raw materials is abundant and the cost is low. At the same time, it solves the problems of urban white pollution and partial treatment and disposal of domestic waste.

Description of drawings

Fig. 1 is a schematic structural diagram of a novel porous bed material circulating fluidized bed gasifier used in the present invention.

Fig. 2 is a schematic diagram of the present invention for combined cooling, heating and power supply in a distributed renewable energy system.

Detailed ways

A method for gasifying biomass and high calorific value garbage in a distributed renewable energy system. The method uses a porous bed material circulating fluidized bed gasifier to produce high calorific value gas. The production steps include:

(1) Put biomass and high calorific value waste into the furnace body with an operating temperature of 600-900°C at a mass ratio of 1:2, the fluidization velocity is greater than 3-5 times the particle terminal velocity, and the equivalent ratio is between 0.2- Between 0.25, biomass and high-calorific-value waste first undergo rapid decomposition to produce gas, coke and tar;

(2) Tar continues to be cracked in a high-temperature environment, and coke is further reduced with CO ₂ and H ₂ O, and the incompletely reacted carbon particles and gas are separated at the outlet, and the gas is sent away as a product through the gas collection device 5; The coke is sent back to the bottom of the fluidized bed 3 by the air pump 10 for combustion with the air, and the heat generated is supplied to the entire gasifier through the steam generator 11 to ensure the endothermic process of pyrolysis and reduction, which basically meets the requirements of reduction and tar cracking;

(3) The residence time of the gas phase in the furnace is between 2-4s, and the residence time of the solid phase in the furnace can reach between 4-6s.

The realization means of the combined gasification method of biomass and high calorific value garbage provided by the present invention will be described in detail below with reference to the accompanying drawings.

Referring to Fig. 1, the present invention takes the porous bed material circulating fluidized bed gasification furnace as research means, the porous bed material circulating fluidized bed gasification furnace used in the method is fixed on the support 12, and its furnace wall is provided with insulation Layer 2, the bottom of the fluidized bed 3 is provided with a porous bed material layer 1, and is respectively connected with the air pump 10 and the steam generator 11 through the external pipeline at the bottom of the fluidized bed 3; a feed inlet is provided at the top of the fluidized bed 3 4, and communicate with the gas collecting device 5 through pipelines; Flowmeters 8 are respectively arranged on the pipelines between the air pump 10 and the steam generator 11 and the fluidized bed 3 . A pressure limiting valve 9 is also provided on the pipeline between the steam generator 11 and the fluidized bed 3 .

Referring to Figure 2, the porous bed material circulating fluidized bed gasifier is used to gasify biomass particles and high calorific value waste, and the high calorific value gas produced provides a distributed renewable energy system for the subsequent combined cooling, heating and power supply. Biomass particles (straw particles) and high calorific value garbage (mainly waste plastics) enter the porous bed material fluidized bed at the same time, and the high calorific value gas generated is processed by the purifier and gas storage tank and then enters the micro gas turbine, and its internal combustion chamber generates Under the action of pressure, the gas expands to do work, drives the gas turbine to generate electricity, and the excess electricity is input to the grid. The high-temperature flue gas discharged from the gas turbine enters the heat exchanger, and after heat exchange with the feed water, part of it is supplied to users for heating and domestic use, and the other part enters the lithium bromide refrigeration mechanism to produce refrigerant water, which then enters the fan coil of the central air conditioner for heat exchange and cooling. The low-temperature flue gas discharged from the heat exchanger is discharged into the atmosphere after anti-pollution treatment, realizing the triple supply of cooling, heating and electricity.

The following examples are all researches on the gas production trend of the combined gasification of biomass and high-calorific waste under different experimental conditions, as the theoretical basis of the present invention.

Example 1

First put zeolite as bed material into the fluidized bed 3 to form a porous bed material layer 1, then take 2-5mm biomass particles (straw particles) and high calorific value garbage with a diameter of less than 8mm after compression molding according to a mass ratio of 1:2, Put it into the furnace body with an operating temperature of 600-900°C from the feed port 4, the feed amount is controlled at 3.78kg/h, the fluidization velocity is greater than 3-5 times the particle terminal velocity, and the equivalent ratio is between 0.2-0.25 During this period, in an oxygen-enriched atmosphere with an oxygen concentration of more _than 40%, straw particles and waste plastics first undergo rapid decomposition to generate gas, coke _and tar; At the outlet, the incompletely reacted carbon particles are separated from the gas, and the gas is sent to the gas collection device 5 as a product, and the coke is sent back to the bottom of the fluidized bed 3 by the air pump 10 for combustion with the air, and the heat generated is passed through the steam The generator 11 supplies the entire gasification furnace to ensure the endothermic process of pyrolysis and reduction, and basically meet the requirements of reduction and tar cracking; the residence time of the gas phase in the furnace is between 2-4s, and the residence time of the solid phase in the furnace It can reach 4-6s. The experimental results found that the gas produced after the combined gasification of biomass particles and high-calorific value waste includes H ₂ , CO, and CH ₄ , C ₂ H ₄ , C ₂ H ₆ and CO _{2 ,} etc., and the total heat of all gases The value reaches 30MJ/m ³ . The calorific value of this gas can meet the calorific value of the fuel required by the micro gas turbine (26.1-93.85MJ/Nm ³ ), and the daily available waste heat of the C30 low-pressure gas-type gas turbine generator set is 7174MJ, which can generate 672KWh of electric energy and meet the requirement of 1800m ² The heat demand of 22 households in the community is 621MJ for bathing and 886MJ for refrigerators. The flow meter 8 and the pressure limiting valve 9 respectively control the air flow and pressure of the test system, and the combined gasification gas is collected by the gas collecting device 5 .

Example 2

Biomass particles (2-5mm) with a fuel feed rate of 3.78kg/h and compression-molded high-calorific-value waste (diameter 8mm) are put into a fluidized bed made of zeolite at a mass ratio of 1:2. The atmosphere (water vapor flow rate is 1.38kg/h) and the reaction temperature are gasified at 600-900°C. It was found that the gas produced by the combined gasification of the two includes H ₂ , CO, CH ₄ , C ₂ H ₄ , C ₂ H ₆ and CO _{2 ,} etc., and the total calorific value of all gases reaches 28MJ/m ³ . The calorific value ^of this gas can meet the calorific value of the fuel required by the micro gas turbine (26.1-93.85MJ/Nm ³ ). The heat demand of 19 households in the community is 580MJ for bathing and 827MJ for refrigerators. Other content is the same as embodiment 1.

Claims (4)

1. the biomass of distribution type renewable energy system and high heating value garbage gasifying method, this method adopt porous bed material circle fluidized-bed gasification furnace to produce the high heating value combustion gas, and it is produced step and comprises:

(1) biomass and high heating value rubbish being put into operating temperature with 1: 2 mass ratio is in 600-900 ℃ the body of heater, between 0.2-0.25, biomass and high heating value rubbish at first take place to decompose fast and generate gas, coke and tar its fluidizing velocity greater than doubly particle terminal velocity of 3-5, equivalence ratio;

(2) tar continues cracking under hot environment, and coke and CO ₂, H ₂O further reduces, and the carbon granules of complete reaction and gas are not separated in the exit, and gas is seen off by gas extractor (5) as product; Coke is sent fluidized-bed (3) bottom back to by pneumatic pump (10) and is burnt with air, and the heat of generation is supplied with whole vapourizing furnace through steam generator (11), to guarantee pyrolysis and reduction endothermic process, basic satisfied reduction and coke tar cracking requirement;

(3) residence time of solid phase in stove can reach between the 4-6s between 2-4s the residence time of gas phase in stove.

2. the biomass of distribution type renewable energy system according to claim 1 and high heating value garbage gasifying method, it is characterized in that: employed in the method porous bed material circle fluidized-bed gasification furnace is fixed on the support (12), its furnace wall is provided with thermal insulation layer (2), fluidized-bed (3) bottom is provided with the porous bed bed of material (1), and is connected with steam generator (11) with pneumatic pump (10) respectively by the external pipeline of fluidized-bed (3) bottom; Be provided with opening for feed (4) at fluidized-bed (3) top, and be communicated with gas extractor (5) by pipeline; Temperature control unit (6) is by the inboard wall of furnace body control linkage of thermopair (7) with close fluidized-bed (3).

3. the biomass of distribution type renewable energy system according to claim 2 and high heating value garbage gasifying method is characterized in that: be respectively equipped with under meter (8) on the pipeline between described pneumatic pump (10) and steam generator (11) and the fluidized-bed (3).

4. the biomass of distribution type renewable energy system according to claim 3 and high heating value garbage gasifying method is characterized in that: also be provided with pressure limiting valve (9) on the pipeline between described steam generator (11) and the fluidized-bed (3).

Images