Hybrid pyrolysis of coal method
Technical field
The present invention relates to a kind of pyrolysis of coal method, particularly relate to a kind of hybrid pyrolysis of coal method.
Background technology
Low-temperature pyrolysis of coal can improve the quality of coal (particularly low-rank coal) under mild conditions, and low temperature pyrogenation technique can be divided into external-heat by the type of heating of body of heater, internal heat type and inside and outside hybrid.The heating medium of external-heat stove does not contact with feed coal, heat imports in process furnace by furnace wall, for raw material pyrolysis, thus almost nitrogen is not had in the coal pyrolysis gas obtained, the quality of pyrolysis gas is better, but because its heat is imported into by furnace wall, its thermo-efficiency is lower, and the investment cost of external-heat pyrolysis oven will far above internal heat type pyrolysis oven.Internal heat type stove can be divided into solid thermal carriers and gaseous heat-carrier by its heating medium.Take gas as the internal heat type pyrolysis oven that thermal source carries out pyrolytic reaction, because feed coal directly contacts with pyrolysis gas, heat exchange efficiency is higher, but owing to containing more nitrogen in heat source gas, the impurity contained in the pyrolysis gas obtained is more, unfavorable to following process.
Summary of the invention
Technical problem to be solved by this invention is to provide a kind of hybrid pyrolysis of coal method, it can obtain the coal tar of high-quality by gas-liquid separation, a nitrogen content in coal gas after separation is low, significantly can reduce scale and the cost of the processing and utilization Facilities Construction device in coal gas later stage.
The present invention solves above-mentioned technical problem by following technical proposals: a kind of hybrid pyrolysis of coal method, and it is characterized in that, it comprises the following steps:
Step one, feed coal enters in mixed pyrolysis stove, directly contact with heating gas, heat exchange generation pyrolytic reaction, meanwhile, the heat exchange in roasting kiln of the high-temperature flue gas that the heat that in roasting kiln, coal-char combustion generates can be generated by coal-char combustion or circulating flue gas heats up and is converted into high-temperature flue gas, brings in the outer hot heat transmitter in mixed pyrolysis stove, with feed coal and pyrolysis gas indirect heat exchange, make up the heat that pyrolysis of coal process is lost; The raw gas that pyrolysis of coal generates enters in gas-liquid separator, obtain coal tar and the raw gas of high-quality, raw gas obtains clean coal gas after gas-cleaning installation purification, most coal gas can supply directly outward, part coal gas is circulated in gas preheater, after the flue gas heat exchange exported with the outer hot heat transmitter of mixed pyrolysis stove, obtain preheating gas, preheating gas enters in mixed pyrolysis stove after entering the further raised temperature in mixed pyrolysis stokehold, and brings in gas-liquid separator by the gaseous product that pyrolytic reaction generates;
Step 2, heat Jiao produced in mixed pyrolysis stove enters in dry quenching(of coke) device, sends in semicoke feed bin by cold flue gas after being lowered the temperature, semicoke is by screening, obtain cheap small-particle fine powder burnt, coke breeze is sent in roasting kiln and is burnt, and the heat part of coke breeze burning is used for heating preheating gas; Remaining heat can be adopted and utilize in two ways, and one is that the high-temperature hot flue gas of coal-char combustion generation and circulating flue gas are mixed into high-temperature flue gas, and another kind makes it to be converted to high-temperature flue gas with indirect mode heating cycle flue gas; High-temperature flue gas is admitted to subsequently in the outer hot heat transmitter of mixed pyrolysis stove and transfers heat to pyrolysis oven, in this process, cooling high-temperature fume is to middle temperature flue gas, middle temperature flue gas continues cooling after gas preheater, become cold flue gas, cold flue gas is admitted in dry quenching(of coke) device to heat up and changes circulating flue gas into.
Positive progressive effect of the present invention is: coal gas and the tar quality of the present invention's production are better, the coal tar of high-quality can be obtained by gas-liquid separation, a nitrogen content in coal gas after separation is low, significantly can reduce scale and the cost of the processing and utilization Facilities Construction device in coal gas later stage, after purification, major part can supply directly outward, the recycle of part coal gas, circulating gas through heating after as thermal source in mixed pyrolysis stove.
Accompanying drawing explanation
Fig. 1 is the functional block diagram of the hardware that the hybrid pyrolysis of coal method of the present invention adopts.
Embodiment
Present pre-ferred embodiments is provided, to describe technical scheme of the present invention in detail below in conjunction with accompanying drawing.
The hybrid pyrolysis of coal method of the present invention comprises the following steps:
Step one, as shown in Figure 1, feed coal (granularity >=3mm) enters in mixed pyrolysis stove E-2, directly contact with heating gas, heat exchange generation pyrolytic reaction, simultaneously, the high-temperature flue gas A1 that the heat that in roasting kiln E-1, coal-char combustion generates can be generated by coal-char combustion or circulating flue gas A4 heat exchange in roasting kiln E-1 heats up and is converted into high-temperature flue gas A1, bring in the outer hot heat transmitter in mixed pyrolysis stove E-2, with feed coal and pyrolysis gas indirect heat exchange, make up the heat that pyrolysis of coal process is lost, the raw gas that pyrolysis of coal generates enters in gas-liquid separator E-6, obtain coal tar and the raw gas of high-quality, raw gas obtains clean coal gas after gas-cleaning installation E-7 purifies, most coal gas can supply directly outward, part coal gas is circulated in gas preheater E-5, after the flue gas heat exchange exported with the outer hot heat transmitter of mixed pyrolysis stove E-2, obtain preheating gas, preheating gas enters mixed pyrolysis stove E-2 and takes a step forward after raised temperature and enter in mixed pyrolysis stove E-2, and the gaseous product (comprising gaseous state coal tar) that pyrolytic reaction generates is brought in gas-liquid separator E-6,
Step 2, heat Jiao produced in mixed pyrolysis stove E-2 enters in dry quenching(of coke) device E-3, send in semicoke feed bin E-4 after being lowered the temperature by cold flue gas A3, semicoke is by screening, obtain cheap small-particle fine powder burnt, coke breeze is sent in roasting kiln E-1 and is burnt, and the heat part of coke breeze burning is used for heating preheating gas; Remaining heat can be adopted and utilize in two ways, and one is that the high-temperature hot flue gas of coal-char combustion generation and circulating flue gas A4 are mixed into high-temperature flue gas A1, and another kind makes it to be converted to high-temperature flue gas A1 with indirect mode heating cycle flue gas A4; High-temperature flue gas A1 is admitted to subsequently in the outer hot heat transmitter of mixed pyrolysis stove E-2 and transfers heat to pyrolysis oven, in this process, high-temperature flue gas A1 is cooled to middle temperature flue gas A2, middle temperature flue gas A2 continues cooling after gas preheater E-5, become cold flue gas A3, cold flue gas A3 is admitted in dry quenching(of coke) device E-3 to heat up and changes circulating flue gas A4 into.In the working cycle of flue gas, realize the cascade utilization of obvious heat of smoke, improve the utilising efficiency of flue gas.
For the unit scale that feed coal input amount is 10t/h, under certain service temperature and pressure, the physical property of feed coal is as shown in table 1.The granularity of the little beans of raw material is greater than 3mm.The material balance of hybrid pyrolysis oven device entirety is as shown in table 2.The composition given gas outward is as shown in table 3, and as shown in Table 3, nitrogen amount contained in the coal gas that this patent technique obtains is little, is conducive to coal gas following process and process.Content of impurities contained in tar is 2%, produces the content (its value is about 5%) of mechanical impurity and coke breeze in tar much smaller than gaseous heat-carrier institute, with the content of impurities (its value is about) in external-heat pyrolytic tar quite.The quality of granule semicoke is also better.
Heat smoke, through mixed pyrolysis stove, gas preheater, dry quenching(of coke), is recycled in roasting kiln, and flue gas, while circulation, achieves the cascade utilization of gas energy, improves the thermo-efficiency of this processing method self.The raw material of roasting kiln burning is the cheap coke breeze produced in technological process, and coke breeze is from the fine particle of semicoke product after screening of dry quenching(of coke).The temperature of combustion chamber also controls by powder coke content and air capacity, is conducive to the regulation and control of device stability.Coal gas component loops is as thermal source in hybrid pyrolysis oven, and heat transfer efficiency is higher, and pyrolysis efficiency is higher, and do not have air or other gas to pass in pyrolytic process, coal gas product qualities is good, and tar quality is also better.The thermal source of mixed pyrolysis stove is made up of internal heat type thermal source and external-heat thermal source two portions, the raw gas that internal heat type thermal source is generated by pyrolysis of coal through gas-liquid separation, purification, preheating and and coal-char combustion stove thermal conversion provide for heating gas; External-heat thermal source provided by the high-temperature hot flue gas in the outer hot heat transmitter of pyrolysis oven.
Those skilled in the art can carry out various remodeling and change to the present invention.Therefore, present invention covers the various remodeling in the scope falling into appending claims and equivalent thereof and change.