CN206872425U - A kind of highly concentrated pickle liquor regenerative system - Google Patents

Abstract

It the utility model is related to a kind of highly concentrated pickle liquor regenerative system, including hydrolysis calcining furnace, two-stage dust removal device, preconcentrator, B grade condensing unit, air cooling tower, hydrochloric acid absorption tower and scrubbing tower；The utility model is directly condensed the flue gas after preconcentrator, high concentration HCl in flue gas is got off with water condensation, avoid the constant boiling point of hydrochloric acid solution, realize regeneration target of the concentration of hydrochloric acid more than more than 22%, the HCl of higher concentration is absorbed in hydrochloric acid absorption tower with water in flue gas after condensation, the hydrochloric acid of concentration needed for acquisition.

Description

A high-concentration pickling waste liquid regeneration system

technical field

The utility model relates to the technical field of pickling waste liquid treatment, in particular to a high-concentration pickling waste liquid regeneration system.

Background technique

During the deep processing of steel, the surface needs to be pickled and derusted. Commonly used pickling solutions are hydrochloric acid and sulfuric acid, and most enterprises currently use hydrochloric acid as the pickling solution. After the steel is pickled with hydrochloric acid, a large amount of pickling waste will be produced. The composition of hydrochloric acid pickling waste liquid is mainly hydrogen chloride, ferrous chloride, water and a small amount of impurities. The content of each component varies with the pickling process, operating temperature, steel type and specification, and generally contains 10-20% of ferrous chloride. , 3-10% hydrogen chloride. Among them, the pickling waste liquid produced by hot rolling of iron and steel generally contains 1-5g/L H ⁺ , 60-250g/L Fe ²⁺ Hazardous Waste List", direct discharge of such waste liquid not only seriously pollutes the environment, but also causes great waste.

According to national environmental protection requirements, pickling waste liquid cannot be discharged directly. The traditional treatment methods include neutralization method, evaporation crystallization method or roasting recovery hydrochloric acid method. The neutralization method is a method commonly used by iron and steel enterprises at present, but its shortcomings are also prominent. On the one hand, it consumes a large amount of alkaline chemicals (such as caustic soda, lime, etc.), and the treatment cost is very expensive; on the other hand, it will generate a large amount of The iron-containing sludge that is difficult to dispose of causes secondary pollution in disguised form to the environment; the evaporation crystallization method is to form dilute hydrochloric acid after heating and evaporating the waste acid solution and condensing it in the condenser, and return it to the workshop for reuse; through evaporation concentration, cooling the concentrated solution to separate out FeCl ₂ crystallized to give a solid product. The advantage of this technology is that it can process waste acid liquid, recover more than 98% of hydrochloric acid, and the concentration of hydrochloric acid is 1% to 4% lower than that of waste liquid; all Fe ²⁺ is discharged in the form of FeCl ₂ solid, and the equipment is simple and the investment is small. The processing cost is low; however, this technology has great environmental and market risks. In order to save costs, the hydrochloric acid used for pickling is mostly by-product hydrochloric acid from other chemical industries, which contains a large amount of organic matter and even toxic substances. Although it has no effect on pickling in the iron and steel industry, ferrous chloride and other products obtained after evaporation and concentration inevitably contain some organic matter or even toxic substances, and FeCl ₂ is generally used as a water purifier. Once the above-mentioned toxic chlorination Products such as ferrous iron are used in water treatment, which will inevitably cause secondary pollution to the treated water, and the consequences will be disastrous. In addition, the limited market demand for water purifiers also seriously limits the application of this technology. The method of roasting and recovering hydrochloric acid organically combines the heating of waste liquid, dehydration, oxidation and hydrolysis of ferrous salt, collection and absorption of hydrogen chloride gas into hydrochloric acid in one system, and has the advantages of large processing capacity, compact facilities and high resource recovery rate. High (up to 98% ~ 99%), high concentration of regenerated acid, less Fe ²⁺ in the acid, high grade of iron oxide (up to 98%) and wide application, so it has been rapidly promoted; at present, domestic There are more than 200 sets of roasting method to recover hydrochloric acid method in continuous operation. The most widely used technology for recovering hydrochloric acid by roasting is Austria's Ruthner process technology, which is mostly used in China. However, as the iron and steel industry has higher and higher requirements for pickling efficiency, it has become a trend to use high-concentration hydrochloric acid as the pickling medium to greatly improve the pickling efficiency. But hydrochloric acid is under the condition of normal pressure, and 22% is its azeotropic concentration, because Ruthner process technology adopts the technology that water absorbs HCl, the concentration of its regenerated hydrochloric acid can't exceed 22%wt, can only reach 18%-～20%wt, Unable to meet the needs of enterprises for regenerated hydrochloric acid with a concentration of more than 22%.

Contents of the invention

The utility model provides a high-concentration pickling waste liquid regeneration system. The flue gas after the pre-concentrator is directly condensed by a secondary condensing device, and the high-concentration HCl and water in the flue gas are condensed to avoid the hydrochloric acid solution. Constant boiling point, to achieve the goal of regenerated hydrochloric acid concentration exceeding 22%, after condensation, the higher concentration of HCl in the flue gas is absorbed by water in the hydrochloric acid absorption tower to obtain the required concentration of hydrochloric acid.

In order to achieve the above object, the utility model adopts the following technical solutions to realize:

A high-concentration pickling waste liquid regeneration system, including a hydrolysis calciner, a secondary dust removal device, a pre-concentrator, a secondary condensation device, an air cooling tower, a hydrochloric acid absorption tower, and a washing tower; the upper flue gas outlet of the hydrolysis calciner The flue gas inlet on the top of the pre-concentrator is connected to the flue gas inlet at the top of the pre-concentrator through the secondary dust removal device composed of a cyclone separator and a multi-tube dust collector; the powder outlets of the hydrolysis calciner, the cyclone separator and the multi-tube dust collector are respectively connected to the pneumatic conveying pipeline and the pneumatic conveying pipeline There is a pneumatic conveying fan on the top; one way of the bottom liquid outlet of the pre-concentrator is connected to the top liquid inlet of the pre-concentrator through a circulating concentration pump, and the other is connected to the top liquid spray gun of the hydrolysis calciner through a feed pump; the concentrated acid on the pre-concentrator The liquid inlet is connected to the high-concentration pickling waste liquid delivery pipeline; the gas outlet of the pre-concentrator is connected to the gas inlet at the bottom of the hydrochloric acid absorption tower through the secondary condensation device composed of the first condenser and the second condenser; the first condenser and the second The liquid outlet of the second condenser is connected to the liquid inlet of the hydrochloric acid mixing tank; the cooling water inlets of the first condenser and the second condenser are connected to the outlet of the air cooling tower through the air-cooling circulation pump, and the inlet of the air-cooling circulation pump is additionally connected to the desalinated water delivery pipeline; the first The cooling water outlet of the condenser and the second condenser is connected to the inlet of the air cooling tower; the liquid outlet at the bottom of the hydrochloric acid absorption tower is connected to the liquid inlet of the hydrochloric acid mixing tank, and the liquid outlet of the hydrochloric acid mixing tank is connected to the hydrochloric acid product delivery pipeline through the hydrochloric acid pump; the hydrochloric acid absorption tower The top gas outlet is connected to the bottom gas inlet of the scrubber through an acid-resistant fan; the bottom liquid outlet of the scrubber is connected to the top liquid inlet of the hydrochloric acid absorption tower and the top liquid inlet of the scrubber through a scrubber pump; the top liquid inlet of the scrubber is also connected to the desalted water delivery pipeline.

Compared with the prior art, the beneficial effects of the utility model are:

1) High-concentration regenerated hydrochloric acid products with a concentration exceeding 22% can be obtained to meet the needs of existing enterprises for high-concentration hydrochloric acid using efficient pickling processes;

2) The technical improvement based on Ruthner technology is widely applicable to new construction projects and existing engineering transformation, and the transformation scheme is simple and easy to implement.

Description of drawings

Fig. 1 is a structural schematic diagram of a high-concentration pickling waste liquid regeneration system described in the present invention.

Fig. 2 is a functional block diagram of a high-concentration pickling waste liquid regeneration system described in the present invention.

In the figure: 1. Hydrolysis calciner 2. Cyclone separator 3. Multi-pipe dust collector 4. Pneumatic conveying fan 5. Pre-concentrator 6. Circulating concentration pump 7. Feed pump 8. First condenser 9. Second condensation 10. Air cooling tower 11. Air cooling circulation pump 12. Hydrochloric acid absorption tower 13. Hydrochloric acid mixing tank 14. Hydrochloric acid pump 15. Acid-resistant fan 16. Washing tower 17. Washing pump

detailed description

The specific embodiment of the utility model will be further described below in conjunction with accompanying drawing:

As shown in Figure 1, a high-concentration pickling waste liquid regeneration system described in the utility model includes a hydrolysis calciner 1, a secondary dedusting device, a pre-concentrator 5, a secondary condensing device, an air cooling tower 10, and a hydrochloric acid absorption tower 12 and a washing tower 16; the upper flue gas outlet of the hydrolysis calciner 1 is connected to the top flue gas inlet of the pre-concentrator 5 through a secondary dust removal device composed of a cyclone separator 2 and a multi-tube dust collector 3; the hydrolysis calciner 1 , the powder outlets of the cyclone separator 2 and the multi-pipe dust collector 3 are respectively connected to the pneumatic conveying pipeline, and the pneumatic conveying pipeline is provided with a pneumatic conveying fan 4; the liquid outlet at the bottom of the pre-concentrator 5 is connected to the pre-concentrator 5 through the circulating concentration pump 6 all the way The top liquid inlet of the other way is connected to the top liquid spray gun of hydrolysis calciner 1 through feeding pump 7; Connect the gas inlet at the bottom of the hydrochloric acid absorption tower 12 by a secondary condensation device consisting of the first condenser 8 and the second condenser 9; the liquid outlet of the first condenser 8 and the second condenser 9 connects the liquid inlet of the hydrochloric acid mixing tank 13 The cooling water inlet of the first condenser 8 and the second condenser 9 connects the outlet of the air cooling tower 10 through the air-cooling circulating pump 11, and the inlet of the air-cooling circulating pump 11 is connected to the desalted water delivery pipeline in addition; the first condenser 8 and the second condenser The cooling water outlet of 9 connects the inlet of air-cooling tower 10; The liquid outlet at the bottom of hydrochloric acid absorption tower 12 connects the liquid inlet of hydrochloric acid mixing tank 13, and the liquid outlet of hydrochloric acid mixing tank 13 connects the hydrochloric acid product outgoing pipeline through hydrochloric acid pump 14; Hydrochloric acid absorption tower 12 The top gas outlet is connected to the bottom gas inlet of the washing tower 16 by the acid-resistant fan 15; the bottom liquid outlet of the washing tower 16 is connected to the liquid inlet at the top of the hydrochloric acid absorption tower 12 and the liquid inlet at the top of the washing tower 16 through the washing pump 27; the liquid inlet at the top of the washing tower 16 is additionally Connect the desalted water delivery line.

As shown in Figure 2, the high-concentration pickling waste regeneration process using a high-concentration pickling waste regeneration system described in the present invention includes the following steps:

1) The high-concentration pickling waste liquid with Fe ion concentration > 150g/L is concentrated by high-temperature flue gas in the pre-concentrator 5, and the pickling waste liquid with Fe ion concentration > 200g/L after concentration enters the hydrolysis roasting furnace 1 for high temperature Decompose, the decomposition temperature is 400～700℃;

2) The high-temperature flue gas containing HCl prepared in step 1) is sequentially sent to the cyclone dust collector 2 and the multi-pipe dust collector 3 for dust removal treatment, wherein more than 95% of the dust is collected and recycled as iron oxide red;

3) Send the gas obtained in step 2) into the pre-concentrator 5, and contact with the high-concentration pickling waste liquid to complete the processes of dust removal, liquid concentration, and gas cooling. The operating temperature of the pre-concentrator 5 is 85-95°C;

4) performing secondary condensation on the gas treated in step 3), the condensation temperatures are respectively 65-75°C and 45-55°C, to obtain high-concentration regenerated hydrochloric acid with a concentration of 23-25%wt;

5) send the gas treated in step 4) into the hydrochloric acid absorption tower 12, absorb it with water, and obtain a high-concentration regenerated hydrochloric acid with a concentration of 23-25% wt; the flue gas after absorbing the HCl gas is sent to the scrubber 16 for washing, The flue gas after washing is discharged up to the standard, and the washing liquid is used as the hydrochloric acid absorption liquid.

The top temperature of the hydrolysis roasting furnace 1 is 350-450°C, the furnace bottom temperature is 650-750°C, and the gauge pressure is -200-300Pa.

The high-concentration pickling waste liquid regeneration system described in the utility model is improved on the existing Ruthner technology. The high-concentration pickling waste liquid is concentrated by high-temperature flue gas in the pre-concentrator 5 and then enters the hydrolysis calciner 1 for further processing. Pyrolysis, the high-temperature flue gas obtained is dedusted by the cyclone dust collector 2 and the multi-tube dust collector 3, and then enters the pre-concentrator 5, and contacts with the pickling waste liquid to be treated. The gas whose temperature is lowered to 85-95 ° C is not directly watered Instead, enter the secondary condensation device 8, 9 to condense, and condense the HCl and water in the flue gas; because the addition of water is avoided, the high-concentration HCl and water can be condensed at the same time, avoiding hydrochloric acid The azeotropic point of the solution realizes that the concentration of regenerated hydrochloric acid exceeds 22%. The condensed flue gas contains HCl with a higher concentration, which is absorbed by a certain proportion of water in the hydrochloric acid absorption tower 12 to obtain hydrochloric acid with a required concentration. The tail gas absorbed by hydrochloric acid is further absorbed through the washing tower 16, and the tail gas is discharged up to the standard.

The following examples are carried out on the premise of the technical solution of the utility model, and detailed implementation and specific operation process are provided, but the protection scope of the utility model is not limited to the following examples. The methods used in the following examples are conventional methods unless otherwise specified.

【Example 1】

1) Preheat the hydrolysis calciner 1 with natural gas as the heat source, and then heat it to the required temperature, wherein the furnace top temperature is 400°C, and the furnace bottom temperature is 700°C; add high-concentration pickling waste liquid into the pre-concentrator 5, While cooling the high-temperature flue gas, it realizes the pre-concentration of high-concentration pickling waste liquid.

The composition of the high-concentration pickling waste liquid to be treated is shown in the following table:

Element Contentg/L Flow Kg/h Remark _FeCl3 47.91 105.402 Fe ³⁺ ＝16.51g/L _FeCl2 340.45 748.99 Fe ²⁺ ＝150.0g/L HCl 75.73 166.606 — H ₂ O 911.1 2004.42 — total 1375.19 3025.418 —

It needs to process 3.025 tons of pickling waste per hour.

2) The components of the pickling waste liquid after pre-concentration by the pre-concentrator 5 are as shown in the table below:

Element Contentg/L Flow Kg/h Remark _FeCl3 63.87 105.3855 Fe ³⁺ ＝22.01g/L _FeCl2 453.96 749.034 Fe ²⁺ ＝200g/L HCl 135.29 223.2285 — H ₂ O 683.32 1127.478 — total 1336.44 2205.126 —

The gas composition after high temperature hydrolysis is shown in the following table:

Element volume% HCl 10.5 H ₂ O 39.8 O ₂ 3.77 N ₂ 42.16 CO ₂ 3.77

The total gas volume is 9800m ³ , and the temperature is 400°C. The gas contains 60kg of Fe ₂ O ₃ . After the secondary dust removal, the dust recovery is 57kg, and the recovery rate reaches 95%.

450kg of red iron oxide powder was collected from the bottom of hydrolysis calciner ₁ , wherein the content of _Fe2O3 was 98.8%wt, the content of Cl was 1.01%wt, and the bulk density was 400kg/ ^m3 .

Composition of the gas components concentrated by the pre-concentrator 5:

Element volume% HCl 7.88 H ₂ O 49.9 O ₂ 3.18 N ₂ 35.5 CO ₂ 3.18

The total gas volume is 6413m ³ /h, the density is 0.818kg/m ³ , and the temperature is 93.5°C.

3) Perform secondary condensation, absorption, and washing:

Wherein the condensation temperature of the first condenser 8 is 70°C, and the condensation temperature of the second condenser 9 is 50°C.

The feed rate of the hydrochloric acid absorption tower 12 is 224.4kg/h, wherein the HCl content is 2%wt.

The amount of hydrochloric acid obtained after secondary condensation and hydrochloric acid absorption is 2629kg/h, and the concentration is 23%wt.

The gas composition after the scrubber 16 is composed of:

Element volume% HCl 1.0×10 ^-3 H ₂ O 8.87 O ₂ 6.95 N ₂ 77.0 CO ₂ 7.18

The total gas volume is 2700m3/h, and the temperature is 41°C.

[Example 2]

1) Preheat the hydrolysis calciner 1 with natural gas as a heat source, and then heat it to the required temperature, wherein the furnace top temperature is 350°C, and the furnace bottom temperature is 650°C; add high-concentration pickling waste liquid into the pre-concentrator 5, While cooling the high-temperature flue gas, realize the pre-concentration of high-concentration pickling waste liquid;

The composition of the treated high-concentration pickling waste liquid is shown in the following table:

Element Contentg/L Flow Kg/h Remark _FeCl3 47.91 105.402 Fe ³⁺ ＝16.51g/L _FeCl2 340.45 748.99 Fe ²⁺ ＝150.0g/L HCl 75.73 166.606 H ₂ O 911.1 2004.42 total 1375.19 3025.418

3.025 tons of pickling waste liquid needs to be processed per hour

2) The composition of the high-concentration pickling waste liquid pre-concentrated by the pre-concentrator 5 is shown in the following table:

Element Contentg/L Flow Kg/h Remark _FeCl3 61.10 105.7 Fe3 ⁺ ＝21.21g/L _FeCl2 435.28 753.0 Fe2 ⁺ ＝191.9g/L HCl 130.1 224.9 H ₂ O 703.52 1172.5 total 1330 2300

The concentrated liquid is subjected to high-temperature hydrolysis, and the composition of the gas after hydrolysis is shown in the following table:

Element volume% HCl 10.5 H ₂ O 39.5 O ₂ 3.95 N ₂ 42.1 CO ₂ 3.95

The total gas volume is 8526m ³ /h, and the temperature is 350°C.

The gas contains 45kg of Fe ₂ O ₃ , the dust recovery is 43.2kg, and the recovery rate reaches 96%.

452 kg of red iron oxide powder was collected from the bottom of the hydrolysis calciner 1, in which the content of Fe ₂ O ₃ was 98.2% wt, the content of Cl was 1.51% wt, and the bulk density was 400 kg/m ³ .

The composition of the gas components concentrated by the pre-concentrator 5 is shown in the table below:

Element volume% HCl 7.83 H ₂ O 48.3 O ₂ 3.58 N ₂ 36.8 CO ₂ 3.49

The total gas volume is 5761m ³ /h, the density is 0.819kg/m ³ , and the temperature is 92.3°C.

3) Perform secondary condensation, absorption, and washing;

Wherein the condensation temperature of the first condenser 8 is 70°C, and the condensation temperature of the second condenser 9 is 50°C.

The feed rate of the hydrochloric acid absorption tower 12 is 224.4kg/h, wherein the HCl content is 2%wt.

The amount of hydrochloric acid obtained after secondary condensation and hydrochloric acid absorption is 2314kg/h, and the concentration is 23%wt.

The composition of the gas after the washing tower 16 is as shown in the table below:

Element volume% HCl 1.0×10 ^-3 H ₂ O 5.52 O ₂ 8.85 N ₂ 74.8 CO ₂ 10.83

The gas volume is 2537m ³ /h, and the temperature is 42°C.

[Example 3]

1) Preheat the hydrolysis calciner 1 with natural gas as the heat source, and then heat it to the required temperature, wherein the furnace top temperature is 450°C, and the furnace bottom temperature is 750°C; the high-concentration pickling waste liquid is added to the pre-concentrator 5, Realize the pre-concentration of pickling waste liquid while cooling the high-temperature flue gas;

The composition of the treated high-concentration pickling waste liquid is shown in the following table:

Element Contentg/L Flow Kg/h Remark _FeCl3 47.91 105.402 Fe ³⁺ ＝16.51g/L _FeCl2 340.45 748.99 Fe ²⁺ ＝150.0g/L HCl 75.73 166.606 H ₂ O 911.1 2004.42 total 1375.19 3025.418

It needs to process 3.025 tons of high-concentration pickling waste per hour.

2) The composition of the high-concentration pickling waste liquid pre-concentrated by the pre-concentrator 5 is shown in the following table:

Element Contentg/L Flow Kg/h Remark _FeCl3 66.90 105.7 Fe ³⁺ ＝22.01g/L _FeCl2 461.7 729.5 Fe ²⁺ ＝200g/L HCl 132.1 208.7 H ₂ O 719.3 1136.1 total 1380 2180.0

After pre-concentration, the liquid is subjected to high-temperature hydrolysis, and the composition of the gas after hydrolysis is shown in the following table:

Element volume% HCl 10.4 H ₂ O 38.71 O ₂ 4.33 N ₂ 42.68 CO ₂ 3.88

The total gas volume is 10593m ³ , and the temperature is 450°C.

The gas contains 70kg of Fe ₂ O ₃ , the dust recovery is 66.5kg, and the recovery rate reaches 95%.

435 kg of red iron oxide powder was collected from the bottom of hydrolysis calciner 1, in which Fe ₂ O ₃ content was 99.1% wt, Cl content was 0.78% wt, and the bulk density was 400 kg/m ³ .

The composition of the gas after passing through the pre-concentrator is shown in the table below:

Element volume% HCl 7.94 H ₂ O 50.41 O ₂ 3.52 N ₂ 34.95 CO ₂ 3.18

The total gas volume is 6610m ³ /h, the density is 0.818kg/m ³ , and the temperature is 93.9℃

3) Perform secondary condensation, absorption, and washing;

Wherein the condensation temperature of the first condenser 8 is 70°C, and the condensation temperature of the second condenser 9 is 50°C.

The feed liquid of the hydrochloric acid absorption tower 12 is 255kg/h, wherein the HCl content is 2%wt.

The amount of hydrochloric acid obtained after secondary condensation and then hydrochloric acid absorption is 2743kg/h, and the concentration is 23%wt.

The composition of the gas after the scrubber 16 is:

Element volume% HCl 1.0×10 ^-3 H ₂ O 8.91 O ₂ 7.69 N ₂ 76.6 CO ₂ 6.80

The gas volume is 2767m ³ /h, and the temperature is 42°C.

The above is only a preferred embodiment of the utility model, but the scope of protection of the utility model is not limited thereto. The equivalent replacement or change of the new technical solution and the concept of the utility model shall be covered by the protection scope of the utility model.

Claims (1)

1. a kind of highly concentrated pickle liquor regenerative system, it is characterised in that including hydrolysis calcining furnace, two-stage dust removal device, pre-concentration Device, B grade condensing unit, air cooling tower, hydrochloric acid absorption tower and scrubbing tower；The top exhanst gas outlet of the hydrolysis calcining furnace leads to successively Cross and connect smoke inlet at the top of preconcentrator with the two-stage dust removal device that multi-tube dust cleaner forms by cyclone separator；Hydrolysis calcining The dust outlet of stove, cyclone separator and multi-tube dust cleaner connects Pneumatic conveying pipeline respectively, and Pneumatic conveying pipeline is provided with gas Power conveying fan；The overhead-liquid that the bottom liquid outlet of preconcentrator connects preconcentrator by circulating concentrating pump all the way enters Mouthful, another way connects the overhead-liquid spray gun of hydrolysis calcining furnace by feed pump；Concentration acid solution entrance connection on preconcentrator High concentration pickle liquor conveyance conduit；The gas vent of preconcentrator passes sequentially through to be made up of the first condenser and the second condenser B grade condensing unit connection hydrochloric acid absorption tower bottom gas inlet；The liquid outlet of first condenser and the second condenser connects The liquid inlet of mixed in hydrochloric acid groove；The cooling water inlet of first condenser and the second condenser connects air cooling by air cooling circulating pump The outlet of tower, air cooling pump entry connect desalted water conveyance conduit in addition；The cooling water of first condenser and the second condenser The entrance of outlet connection air cooling tower；Hydrochloric acid absorption tower bottom liquid outlet connects the liquid inlet of mixed in hydrochloric acid groove, mixed in hydrochloric acid The liquid outlet of groove connects hydrochloric acid product by hydrochloric acid pump and sends pipeline outside；The outlet of hydrochloric acid absorption tower top gas passes through acidproof blower fan Connect the bottom gas inlet of scrubbing tower；The bottom liquid outlet of scrubbing tower connects hydrochloric acid absorption tower overhead-liquid by washing pump Liquid inlet at the top of entrance and scrubbing tower；Liquid inlet connects desalted water conveyance conduit in addition at the top of scrubbing tower.