CN101927207A - Process for preparing fine rubber powder by crushing waste and old tires at low temperature - Google Patents

Abstract

The invention discloses a process for preparing fine rubber powder by crushing waste and old tires at the low temperature. The process comprises the following steps: crushing the waste and old tires into rubber power with granularity of being less than or equal to 50 meshes at normal temperature for later use; inputting the minus 162 DEG C liquefied natural gas (LNG) in a low-temperature storage tank to a cooler and a precooler; cooling the air in the cooler and the precooler to about minus 14 DEG C from the normal temperature; after the LNG recovers to the normal temperature, conveying the LNG to a natural gas storage tank; introducing the cooled air at minus 140 DEG C into a refrigerating chamber, and inputting the prepared rubber powder into the refrigerating chamber to refrigerate and embrittle the rubber powder, wherein the refrigeration temperature is minus 80 DEG C; and then conveying the rubber powder to a low-temperature crusher for crushing so that the granularity of the rubber powder is between 180 and 200 meshes. The rubber granules and the low-temperature air are in full contact, so that the heat is efficiently transferred and the rubber granules are refrigerated to the embrittling temperature.

Description

A kind of technology of preparing fine rubber powder by crushing waste and old tires at low temperature

Technical field

The invention belongs to the preparation method of fine glue powder, particularly a kind of technology of preparing fine rubber powder by crushing waste and old tires at low temperature.

Background technology

The method for preparing at present fine glue powder mainly contains the low-temperature grinding method of normal temperature crushing up, liquid nitrogen refrigerating, the low-temperature grinding method of utilizing air swell refrigeration, wet method or solution comminuting method etc.

Normal temperature crushing up generally is meant at normal temperature or is higher than a kind of comminuting method of making rubber powder under the temperature of normal temperature by the mechanism crushing rubber.Its pulverization principle be by mechanical shear stress effect to rubber push, mill, thereby shearing and tearing be its cut-out and crushing.Its general technology is: earlier waste old is broken into the blob of viscose about 50mm, with boulder crusher they are ground into micelle about 20mm then, isolate steel wire and fiber in the micelle with magnetic separator and winnowing machine simultaneously, further grind the rubber powder of making 40-200 μ m with fine crusher at last.Comparatively Xian Jin technology has: the continuous comminuting method of damaged tire, extrude comminuting method, high pressure comminuting method, normal temperature and soak and mix comminuting method etc.The product cut size that this method makes is big, the physical property that purposes is narrow, reduced rubber powder.

The low-temperature grinding method of liquid nitrogen refrigerating

Liquid nitrogen refrigerating has the following advantages: the liquid nitrogen boiling point is-196 ℃, good refrigeration effect; Liquid nitrogen is an inert substance, can prevent the material oxidation; Liquid nitrogen can directly be imported in the pulverizer, reduces pre-cool time, has simplified the device flow process.Its technology of low-temperature grinding method of liquid nitrogen refrigerating roughly can be classified as two kinds: a kind of is directly to utilize liquid nitrogen frozen that waste rubber goods is refrigerated to below the vitrification point afterwards it to be pulverized; Another kind is the disintegrating process of normal temperature, low temperature and usefulness, promptly earlier at normal temperatures waste rubber goods is crushed to certain particle diameter, is sent to and carries out low-temperature grinding in the Lowtemperaturepulverizer.

Utilize the low-temperature grinding method of air swell refrigeration

China is the main researcher of this technology.Its technological core is the application of air turbine swell refrigeration technology waste old low-temperature grinding in rubber industry.Basic principle is that air is compressed in air compressor machine and has certain pressure, after separation, drying, enter the coaxial compressor second-compressed of decompressor, pass through second-compressed subsequently, feed heat-exchange apparatus and carry out cold and hot exchange, reduce temperature, through the turbo-expander swell refrigeration, temperature reaches below-120 ℃; Meanwhile, junked tire is through coarse crushing, in small, broken bits, and by magnetic separation, selection by winnowing, screening, removes steel wire and fiber, obtains the micelle of 2～4mm particle diameter.This micelle carries out dynamically freezingly with cold air in freezing fluid bed, and its temperature is reached below the vitrification point, separates after pulverizing backheat through Lowtemperaturepulverizer, and the rubber powder warehouse entry divides grade packaged, and air returns air compressor machine recirculation.This technology makes full use of cold and dry air, and is low in energy consumption, can move continuously and can realize automated production.Research and development unit of the existing many families of China is used for this technology the low-temperature production process of rubber powder now.The prepared nitrogen products consumption of above-mentioned two kinds of low-temperature grinding methods is big, the cost height.

Wet method or solution comminuting method

Wet method or solution comminuting method are a kind of methods of scrap rubber being pulverized the production rubber powder in media such as solvent or solution.The disintegrating apparatus that this method mainly adopts is the abrasive disk type colloid mill.This method complex process, product cost height, popularization difficulty.

Summary of the invention

The purpose of this invention is to provide a kind of crush efficiency height, the technology of the uniform preparing fine rubber powder by crushing waste and old tires at low temperature of grinding particle size.

For achieving the above object, the technology of a kind of preparing fine rubber powder by crushing waste and old tires at low temperature of the present invention is finished by following steps:

One, it is standby junked tire to be crushed at normal temperatures granularity≤50 purpose rubber powders;

Two, with liquified natural gas LNG input cooler, the forecooler of the temperature in the refrigerated storage tank at-162 ℃, the air in cooler and the forecooler is cooled to about-140 ℃ by normal temperature, liquified natural gas self re-heat to normal temperature is transported to the natural gas basin;

Three, will feed in the refrigerating chamber through the temperature of supercooling Cryogenic air in the step 2 at-140 ℃, the rubber powder that makes in the step 1 is input in the refrigerating chamber, cryogenic temperature is-80 ℃, freezing rubber powder, make it embrittlement, and then deliver to Lowtemperaturepulverizer and pulverize, make its granularity reach the 180-200 order;

Four, in the step 3 Cryogenic air of used refrigerating chamber after freezing come out, from as-80 ℃, replenish again behind the precooled air filter by filter after, be transported to aerial cooler by air blast and recycle once more.

Cryogenic pulverization is applicable to the material that is difficult for pulverizing under the broken normal temperature, freezing the becoming after the vitrification point of these materials is highly brittle, be easy to pulverize, power consumption is low, and can utilize the difference of different material brittle temperature to realize selective crushing, heat-sensitive substance can not be subjected to oxidation and go bad.In addition, the main source of waste old is a junked tire, account for 60%-70%, the cryogenic pulverization technology is used to pulverize tire and can directly handles whole tire, rubber is than steel wire and the easier pulverizing of cord under the low temperature, steel wire and cord seldom are damaged during processing, save stripping and slicing like this, grind and separate the operation of iron filings and fiber, and efficient greatly improves.Allow micelle fully contact with Cryogenic air, efficient heat transfer makes micelle freezing, reaches brittle temperature, and this is the important step of low-temperature grinding.The pressure of Cryogenic air height, in which way with the rubber powder contact heat-exchanging, need calculate and do structural consideration, Cryogenic air can recycle simultaneously.

Cryogenic crushing process calculates

The low-temperature grinding process is calculated the cold balancing that will realize exactly between rubber powder, air and the LNG, reaches optimum heat exchange effect and cryogenic energy utilization.Should satisfy following energy relationship formula between 3 kinds of media

$q_{\mathrm{LNG}}{\stackrel{\·}{m}}_{\mathrm{LNG}}=K_a{C}_{\mathrm{pa}}(t_a^{\′}-t_a^{\′\′}){\stackrel{\·}{m}}_a=K_r{q}_r{\stackrel{\·}{m}}_r$

q _LNG＝γ _LNG+182C _pNG

In the following formula, q _LNGFor the LNG of unit mass reaches 20 ℃ of heats that normal temperature absorbed after by-162 ℃ of gasifications, comprise latent heat and sensible heat, kJ/kg;

Be the amount of vaporization of the LNG of unit interval, kg/min; K _a, K _rBe coefficient; C _PaBe the specific heat at constant pressure of air, kJ/ (kg.K); T ' _a, t " _aOut temperature when being respectively air and LNG heat exchange, ℃;

Be the internal circulating load of air, kg/min; q _rFor the rubber powder of unit mass freezing by normal temperature to being lower than-70 ℃ of needed colds, kJ/kg;

Be the treating capacity of rubber powder, kg/min; γ _LNGBe the gasification latent heat of LNG, kJ/kg; C _PNGBe the specific heat at constant pressure of natural gas, kJ/ (kg.K).

For handling 10000t junked tire system year, can produce rubber powder 6000t, steel wire 3500t, fiber 500t.

Physical parameter, q _r=425kJ/kg, C _Pa=1.05kJ/ (kg.K), γ _LNG=509.74kJ/kg, C _PNG=1.56kJ/ (kg.K), atmospheric density ρ _a=1.29kg/m ³, and utilize two formula to calculate flow and each node temperature of flow process of material, see Table 1.

Table 1 preparing fine rubber powder by crushing waste and old tires at low temperature technological process major parameter

Concrete real-time mode

Embodiment

One, it is standby the 500kg junked tire to be crushed at normal temperatures granularity≤50 purpose rubber powders;

Two, with liquified natural gas LNG input cooler, the forecooler of the temperature in the refrigerated storage tank at-162 ℃, the air in cooler and the forecooler is cooled to about-140 ℃ by normal temperature, liquified natural gas self re-heat to normal temperature is transported to the natural gas basin;

Three, will feed in the refrigerating chamber through the temperature of supercooling Cryogenic air in the step 2 at-140 ℃, the rubber powder that makes in the step 1 is input in the refrigerating chamber, cryogenic temperature is-80 ℃, freezing rubber powder, make it embrittlement, and then deliver to Lowtemperaturepulverizer and pulverize, make its granularity reach the 180-200 order;

Four, in the step 3 Cryogenic air of used refrigerating chamber after freezing come out, from as-80 ℃, replenish again behind the precooled air filter by filter after, be transported to aerial cooler by air blast and recycle once more.

Claims (1)

1. the technology of a preparing fine rubber powder by crushing waste and old tires at low temperature, it is characterized in that: described technology is finished by following steps,

One, it is standby junked tire to be crushed at normal temperatures granularity≤50 purpose rubber powders;

Two, with liquified natural gas LNG input cooler, the forecooler of the temperature in the refrigerated storage tank at-162 ℃, the air in cooler and the forecooler is cooled to about-140 ℃ by normal temperature, liquified natural gas self re-heat to normal temperature is transported to the natural gas basin;

Three, will feed in the refrigerating chamber through the temperature of supercooling Cryogenic air in the step 2 at-140 ℃, the rubber powder that makes in the step 1 is input in the refrigerating chamber, cryogenic temperature is-80 ℃, freezing rubber powder, make it embrittlement, and then deliver to Lowtemperaturepulverizer and pulverize, make its granularity reach the 180-200 order;

Four, in the step 3 Cryogenic air of used refrigerating chamber after freezing come out, from as-80 ℃, replenish again behind the precooled air filter by filter after, be transported to aerial cooler by air blast and recycle once more.