CN101428820A

CN101428820A - Process for recycling liquid ammonia from coke oven gas

Info

Publication number: CN101428820A
Application number: CNA2008102378461A
Authority: CN
Inventors: 李大路
Original assignee: Individual
Current assignee: Individual
Priority date: 2008-12-06
Filing date: 2008-12-06
Publication date: 2009-05-13

Abstract

The invention discloses a process method for recycling liquid ammonia from coke-oven gas. The process method comprises a washing process by an ammonia washing tower, a normal atmosphere ammonia distillation process, a low-concentration ammonia pressurizing distillation and concentration process, a pure liquid ammonia product preparation process and an ammonia distillation waste water recycling process. The invention has the advantages of reducing construction investment, changing product structure of coke-oven plant, increasing economic benefit for enterprise, using a heat exchanger reasonably, fully utilizing the afterheat of waste liquid at the tower bottom, saving heat source, and realizing cyclic utilization of waste liquid and water source conservation.

Description

The processing method of recycling liquid ammonia from coke oven gas

Technical field

The present invention relates to chemical field, relate in particular to the ammonia reclaiming process of coke-oven gas.

Background technology

At present the ammonia in coke-oven plant's coke-oven gas reclaims dual mode is arranged, and middle-size and small-size coke-oven plant generally adopts the washing ammonia process, and what absorbed ammonia washes ammoniacal liquor normal pressure ammonia still process again, produces the weak ammonia that contains ammonia about 15%.Because weak ammonia product low grade is difficult for storing, so at a discount, large-scale coke-oven plant has mostly adopted the sulphur ammonia process to produce ammonium sulfate, and this technology deficiency is that construction investment is big, cost is high, quality product is low, economic benefit is low.

Summary of the invention

For solving the not enough problem of above-mentioned recovering ammonia technique and ammonolysis product, the invention provides a kind of processing method of on the basis of reclaiming the production weak ammonia, producing purity 99.9% above liquefied ammonia.

For achieving the above object, processing method of the present invention is:

1, comprises Ammonic washing tower washing process and normal pressure ammonia distillation process, obtain 0.5% rich ammoniacal liquor by the ammonia in the Ammonic washing tower washing post-absorption coal gas, rich ammoniacal liquor is sent to ammonia still carry out normal pressure ammonia still process, the ammonia steam of being discharged by normal pressure ammonia still top send condenser condenses, produces 15% lower concentration ammoniacal liquor after the condensation; Its feature also comprises:

2, lower concentration ammoniacal liquor enters the distilled ammonia wastewater of discharging ammoniacal liquor preheater and ammonia still bottom and carries out heat exchange, lower concentration ammoniacal liquor is heated to 60 ℃, send into the ammoniacal liquor well heater again, heat more than 90 ℃ with saturated vapo(u)r, again with the aqua ammonia pump 1.6-2.0Mpa that pressurizes, send into and concentrate the ammonia still pressure distillation and concentrate.

3, concentrating ammonia still adopts the hydronic method of reboiler that lower concentration ammoniacal liquor is heated to 150-160 ℃, the ammonia steam that cat head steams send overhead condenser with 32 ℃ of water quench, the liquid that condensation is got off enters and concentrates ammonia still backflow continuation heating, uncooled ammoniacal liquor obtains the liquefied ammonia product of purity more than 96% after the ammoniacal liquor condenser is with 16 ℃ of chilled water coolings.

4, concentrate the distilled ammonia wastewater of discharging at the bottom of the ammonia still and enter the low concentration ammonia water preheater, utilize preheating to remove to heat lower concentration ammoniacal liquor, the distilled ammonia wastewater temperature is reduced to below 40 ℃ after the heat exchange, and entering behind the waste water sloptank again, the pumping Ammonic washing tower carries out reuse.

Above-mentioned concentrated ammonia still thermal source is the 4-5kg/cm that is sent here by heat conducting oil boiler ²Low-pressure steam, 350 ℃ superheated vapour after the tube furnace heating again.

The advantage of this processing method is: 1, organically combine and produce the high ammonolysis product of purity with coke-oven plant washing ammonia process, construction investment few (only for the sulphur ammonia process invest 60%); 2, changed coke-oven plant's product structure, strengthened economic benefit of enterprises; 3, the rate of recovery height of simple, the easy handling of technology, ammonia; 4, rationally used heat exchanger, make full use of waste liquid at the bottom of the tower waste heat, saved thermal source, the recycle that realized waste liquid simultaneously saves the water source.

Description of drawings

Fig. 1 is a liquefied ammonia technological process of production synoptic diagram of the present invention.

Embodiment

With reference to accompanying drawing, the liquefied ammonia technological process of production is described as follows:

1, from the coke-oven gas of desulfurization workshop section, in Ammonic washing tower from bottom to top with 28 ℃ cyclic ammonia water counter current contact of one, two, three section spray, contained ammonia is recycled ammoniacal liquor and absorbs in the coal gas.To obtain concentration be 0.5% rich ammoniacal liquor through washing ammonia.

2, with the ammonia still process water pump rich ammoniacal liquor is delivered to one section and remove oil-cleaning system, further remove impurities in the rich ammoniacal liquor through the ammoniacal liquor strainer again, obtain rich or poor chlorine water to remove wet goods impurity contained in the rich ammoniacal liquor.

3, rich or poor ammoniacal liquor is delivered to rich or poor ammoniacal liquor interchanger, ℃ delivered to the ammoniacal liquor well heater, with saturation steam rich ammoniacal liquor is heated to 98 ℃ and enters 1# and the distillation of 2# ammonia still with the distilled ammonia wastewater heat exchange to 60 that at the bottom of 1#, 2# ammonia still, comes;

4, the ammonia vapour that steams enters the ammonia still overhead condenser separately, recirculated water cooling with 32 ℃, the liquid that condensation is got off enters the ammonia still process cat head separately and refluxes, uncooled ammonia vapour enters ammonia vapour condensate cooler and cools off with 16 ℃ chilled water, the ammoniacal liquor of the concentration 15-18% that obtains, deliver to two sections again and remove oil-cleaning system and remove wet goods impurity contained in the ammoniacal liquor, obtain raw material ammonia water, then to the raw material ammonia tank.

5, the distilled ammonia wastewater of discharging at the bottom of the tower in rich or poor ammoniacal liquor interchanger with rich ammoniacal liquor heat exchange after, temperature is reduced to about 70 ℃ and is entered gaseous effluent cooler, enter the wastewater disposal basin sloptank with the cooling of 32 ℃ recirculated waters to 40 ℃, wherein a part goes Ammonic washing tower to wash ammonia usefulness, and a part is gone biochemical treatment.

6, be the raw material ammonia water of 15-18% with concentration in the raw material ammonia tank, deliver to the ammoniacal liquor preheater with the ammonia still process force (forcing) pump, with the distilled ammonia wastewater heat exchange that at the bottom of concentrated ammonia still, comes, after raw material ammonia water is heated to 98 ℃, enter concentrated ammonia still, raw material ammonia water is again through tower bottom reboiler, indirect heating to 150～160 ℃, and the thermal source of reboiler is from heat conducting oil boiler.With ammonia steam straight run distillation, the ammonia vapour that is steamed in concentrating ammonia still is gone into ammonia still process upgrading tower overhead condenser to raw material ammonia water, cools off with 32 ℃ recirculated waters in concentrating ammonia still, and the liquid that condensation is got off is gone into to concentrate the ammonia still process cat head and refluxed, and uncooledly (contains NH ₃～96%) ammoniacal liquor enters the liquefied ammonia that becomes after ammonia condenser cools off with 16 ℃ chilled water more than 96%.Liquefied ammonia is delivered to liquid ammonia storage tank (V0101) store international sale.

7, concentrate the distilled ammonia wastewater of discharging at the bottom of the ammonia still in the raw material ammonia water preheater with the raw material ammonia water heat exchange after, temperature is reduced to about 40 ℃ and is entered the waste water sloptank.Distilled ammonia wastewater in the waste water sloptank is washed aqua ammonia pump with three sections and is delivered to Ammonic washing tower top and do and wash the ammonia moisturizing and recycle.

Claims

1, a kind of processing method of recycling liquid ammonia from coke oven gas, comprise Ammonic washing tower washing process and normal pressure ammonia distillation process, obtain 0.5% rich ammoniacal liquor by the ammonia in the Ammonic washing tower washing post-absorption coal gas, rich ammoniacal liquor is sent to ammonia still carry out normal pressure ammonia still process, the ammonia steam of being discharged by normal pressure ammonia still top send condenser condenses, produce 15% lower concentration ammoniacal liquor after the condensation, it is characterized in that, it also comprises following processing step:

The distilled ammonia wastewater that lower concentration ammoniacal liquor enters ammoniacal liquor preheater and the discharge of ammonia still bottom carries out heat exchange, lower concentration ammoniacal liquor is heated to 60 ℃, sends into the ammoniacal liquor well heater again, heat more than 90 ℃ with saturated vapo(u)r, again with the aqua ammonia pump 1.6-2.0Mpa that pressurizes, send into and concentrate the ammonia still pressure distillation and concentrate;

Concentrating ammonia still adopts the hydronic method of reboiler that lower concentration ammoniacal liquor is heated to 150-160 ℃, the ammonia steam that cat head steams send overhead condenser with 32 ℃ of water quench, the liquid that condensation is got off enters and concentrates ammonia still backflow continuation heating, uncooled ammoniacal liquor is after the ammoniacal liquor condenser is with 16 ℃ of chilled water coolings, obtain the liquefied ammonia product of purity more than 96%, described concentrated ammonia still thermal source is the 4-5kg/cm that is sent here by heat conducting oil boiler ²Low-pressure steam, 350 ℃ superheated vapour after the tube furnace heating again;

Concentrate the distilled ammonia wastewater of discharging at the bottom of the ammonia still and enter the low concentration ammonia water preheater, utilize preheating to remove to heat lower concentration ammoniacal liquor, the distilled ammonia wastewater temperature is reduced to below 40 ℃ after the heat exchange, and entering behind the waste water sloptank again, the pumping Ammonic washing tower carries out reuse.