GB2052701A

GB2052701A - Method of Quenching Hot Bulk Material

Info

Publication number: GB2052701A
Application number: GB8015166A
Authority: GB
Original assignee: Eschweiler Bergwerks- Verein
Current assignee: Eschweiler Bergwerks- Verein
Priority date: 1979-06-23
Filing date: 1980-05-07
Publication date: 1981-01-28
Also published as: FR2459825A1; JPS565887A; NL8002892A; SE8003868L; AU5846780A; YU162280A; IT8022796A0; PL225030A1; IT1131330B; BE883912A; BR8003865A; DE2925439A1

Abstract

Coke is quenched with water, from tank 7, in quenching container 1 and the resulting quenching vapours at about 700 DEG C pass to separator 2 for preliminary dust removal, thence to a waste heat boiler 3 which superheat extraction produces steam which is stored in container 4 for consumer use. Condensation of the vapour and residual dust precipitation occurs in condenser 5. The condensate passes, by way of filter 6, back to the tank 7 for reuse. Permanent gases from the vapour pass to container 10 from which they move through a sulphur purifier 11 whereafter the resultant hydrogen- containing gas is available for chemical processing or heating. The permanent gas may pass to a purifying arrangement 12 without encountering the container 10, and the quenching vapour, as it passes from the quenching container 1, may pass directly to a gas purifying stage 15. <IMAGE>

Description

SPECIFICATION Method of Quenching Hot Bulk Material This invention relates to a method of quenching hot bulk material, such as coke, by means of a liquid flowing from above downwards through the bulk material, in which the bulk material is isolated from external air, and the vapour created from the quenching liquid is carried off in parallel flow with the quenching liquid.

The quenching of hot bulk materials, more especially coke, is effected in open or closed quenching vessels, in which uniform sprinkling with quenching liquid, over the bulk material, is effected. The quenching liquid evaporates partially and abstracts heat from the hot bulk material. The vapour forming from the quenching liquid is conducted into the open by way of a chimney.

This mode of procedure, more especially in the case of coke quenching, has the following disadvantages: The quenching vapour forming in the bulk material entrains very fine powdery material into the atmosphere.

As a result of gasification reactions taking place between the quenching liquid and the bulk material, gaseous reaction products are formed; in the case of coke, for example, these are H2, CO, CO2, H2S and SO2. These gaseous reaction products are also carried off into the atmosphere and in addition represent a ioss of energy.

Since the quenching agent escapes into the open air as vapour, it must again and again be replaced by fresh quenching agent, often by costly potable water.

A particular aggravating disadvantage consists in that the environment of the quenching plant is inconvenienced, over a wide area, by clouds of water vapour having a strongly acid character, and it leads to considerable corrosion in the regions where the quenching vapours condense.

In the case of coke quenching, the acid character of the vapours can be attributed to the following associations: In the case of high-temperature coke, sulphur is present in the mass, predominantly as an organic compound. The hydrogen formed during the quenching process, as a result of the water gas reaction, is initially, i.e. in the 'status nascendi', in a position to reduce the sulphur near the surface from the carbon compound. This process takes place, in the case of coke quenching, both in open and in closed quenching vessels. For example, it has been observed, in the case of a coke which prior to quenching contained about 1 OKp sulphur per tonne, that after the quencing process had been concluded about 0.1 Kp sulphur per tonne had been lost. This amount of sulphur had been converted into hydrogen sulphide.

In the use of traditional open quenching wagons, during the quenching process, water gas (and with it the above-discussed hydrogen sulphide) partially burns off. About 50 percent of the hydrogen sulphide is converted into SO2. The remaining 50 percent leaves the chimney even as H2S.

With regard to the SO2 which is formed, with the existing temperature, the condensation processes and the supply of oxygen in the quenching tower, the essential conditions for wet catalysis are fulfilled. From this there arise the low PH-value and the highly corrosive effects of the quenching vapour clouds.

The invention has as its objecrto provide a method of quenching hot bulk material in which no inconveniencing quenching agent vapours lead to emissions which damage the environment, and in which, instead, heat, dust and gas contained in the quenching agent vapours can be utilised and/or destroyed.

With this object in view the present invention provides a method of quenching hot bulk material, such as coke, by means of a liquid which flows from above downwardly through the bulk material, in which the bulk material is isolated or screened from outside air and the vapour created from the quenching liquid is carried off in parallel flow with the quenching liquid, characterised in that the superheat of the quenching vapour, which is carried off in canalised manner without the inclusion of air, is used to produce operating steam which is utilisable in consumers, and the quenching vapour is subsequently completely condensed, solid substances contained in the quenching vapour being precipitated with the condensate.

In accordance with a development of the method of the invention, the quenching vapour carried off is initially fed, for preliminary dust removal, to a separator, before superheat is abstracted from the quenching vapour.

Any condensation heat still remaining in the quenching vapour after abstraction of superheat can be transferred in a particularly advantageous manner to a hot-water circuit.

In the method of the invention, the solid substances precipitated in the condensate can be excluded without special difficulties, so that the condensate can be used afresh as quenching agent.

In accordance with a further development of the method of the invention, permanent gases contained in the quenching vapour are separated out, trapped, subjected to cleaning and made useful for subsequent chemical processes or used for heating purposes.

The permanent gases separated out from the quenching vapour may, instead, advantageously be introduced continously into coke-oven plant crude gas and be used, after cleaning, for underfiring purposes.

The problem underlying the invention, namely avoidance of emissions which are harmful to the environment and, instead, to utiiise the energies contained in the quenching vapour, can, in the case where the method is for quenching coke using water flowing from above downwards through the coke and in which the coke is isolated from outside air, may also be solved in accordance with the invention by feeding the vapour, forming from the water, in a canalised manner and without the inclusion of air, directly, to a water gas plant, impurities, entrained by the vaprour and not subjected to the gasification, being separated out in a subsequent cleaning (or purification) stage together with impurities in the produced gas, and the gases contained in the vapour being fed to the water gas produced by the quenching.

The advantages which can be achieved with the method in accordance with the invention, more especially in the case of the quenching of coke, are as follows:- Dusts and gases, harmful to the environment, do not pass into the atmosphere.

The gas is cleaned of sulphur compounds and then used in the sense of energy saving as heating gas or for chemical processes.

The neighbourhood of the quenching plant is not inconvenienced by condensing quenching vapours having a strongly corroding effect.

The condensed quenching liquid can be used afresh for quenching purposes. From this there emerges a considerable saving in water.

Superheat and condensation heat contained in the quenching vapours can be won back almost completely.

The significance, harmless to the environment and economical as regards energy, of the method in accordance with the invention will more readily be understood from the following numerical example: A coking plant with an average capacity of 2,000 tato of coke is operated in accordance with conventional quenching techniques with the following energy losses and emissions: Energy losses: Water gas 100,000 Nm3/24 h Heat energy contained in the quenching vapours: 2,200 GJ Emmisions: Dust 200 Kp/24 h Sulphur in the form of: H25 100Kp/24h SP2 100Kp/24h The above mentioned energies can, in accordance with the method in accordance with the invention, be made useful as to 80 percent thereof, and emissions which are harmful to the environment can be completely avoided.

A coke quenching plant is shown schematically in the drawings as an exemplified embodiment for carrying out the method in accordance with the invention, and is described in more detail herein under:- Intermittently-accruing coke-quenching vapours leave a quenching container 1 at about 7000C and are largely freed preliminary from dust in a separator 2. From the separator 2, the vapours are fed to a waste heat boiler 3, in which the free pipeline cross-section is adjustable by means of a shut-off member 13. In the waste heat boiler 3, the superheat of the quenching vapour is utilised to produce operating vapour or process steam. In this, the temperature of the quenching vapour drops to about 3000C. The operating steam (12 bar saturated steam) is stored in a container 4 and is fed from this to consumers (not shown).

In a condenser 5, which is connected subsequent to the waste heat boiler 3, the quenching vapour is completely condensed and the residual dust is precipitated with the condensate.

In a fiiter 6, the solid substances are separated from the condensate and the condensate is fed to a quenching-water storage container 7 from which it is removed as quenching agent for the quenching container 1.

In the condenser 5, superheat possibly still present in the quenching vapour and the condensation heat is transferred to a hot-water circuit. For this, the hot water is collected in a container 8 and forced from the latter through heat consumers 16, by way of which it gives off absorbed heat, and passes into a storage container 9, in which it is kept available for the next cycle (or circulation).

The permanent gases contained in the quenching vapour are trapped in a container 10 and conducted from there by way of a sulphur purification arrangement 11. The hydrogencontaining gas, purified in this way, is available for chemical processes or for heating purposes.

The permanent gases can alternatively be fed, without the interpolation of a gas container 10, directly by way of a purifying arrangement 12 to coke-oven plant crude gas and be used, after a conventional purification process, for underfiring purposes.

As an alternative the possibility also exists of feeding the unpurified quenching vapour immediately after leaving the quenching container 1 for example to a water gas plant 1 which is indicated in broken lines. The impurities entrained by the quenching vapour, insofar as they are not subjected to the gasification, are removed in a subsequently-connected purifying stage 1 5 together with impurities of the gas produced. The gases contained in the quenching vapour are added to the water gas produced. In the case of this alternative mode of procedure, too, emissions of dust and gas as well as inconveniences of the neighbourhood by quenching clouds are avoided in a most effective manner.

Claims

1. A method of quenching hot bulk material, such as coke, by means of a liquid which flows from above downwardly through the bulk material, in which the bulk material is isolated or screened from outside air and the vapour created from the quenching liquid is carried off in parallel flow with the quenching liquid, characterised in that the superheat of the quenching vapour, which is carried off in canalised manner without the inclusion of air, is used to produce operating steam which is utilisable in consumers, and the quenching vapour is subsequently completely condensed, solid substances contained in the quenching vapour being precipitated with the condensate.

2. A method as claimed in claim 1, characterised in that the carried off quenching vapour is fed initially, for preliminary dust removal, to a separator, before the superheat is abstracted from the quenching vapour.

3. A method as claimed in claim 1 or 2, characterised in that condensation heat remaining in the quenching vapour after abstraction of the superheat is transferred to a hot-water circuit.

4. A method as claimed in claim 1, 2 or,3, characterised in that solid substances precipitated in the condensate are separated out and the condensate is used afresh as quenching means.

5. A method as claimed in any preceding claim characterised in that permanent gases contained in the quenching vapour are separated out, trapped, subjected to cleaning and made useful for chemical processes or used for heating purposes.

6. A method as claimed in any of claims 1 to 4, characterised in that permanent gases separated out from the quenching vapour are introduced continuously into coke-oven plant crude gas and are used after cleaning for underlying purposes.

7. A method of quenching hot coke with water flowing from above downwardly through the coke, in the coke is isolated or screened off from external air, characterised in that the vapour, forming from the water, is fed, in canalised manner and without the inclusion of air, directly to a water gas plant, impurities, entrained by the vapour and not subjected to the gasification, being separated out in a subsequent cleaning stage together with impurities in the produced gas, and the gases contained in the vapour being fed to the water gas produced.

8. A method of quenching hot bulk material as claimed in claim 1 and substantialiy as hereinbefore described by way of example.