US20160060553A1

US20160060553A1 - Reformed gas as fuel for primary reformer during startup

Info

Publication number: US20160060553A1
Application number: US14/787,314
Authority: US
Inventors: Shehzada Khurram; Ali Essa Alhammad
Original assignee: Saudi Basic Industries Corp
Current assignee: Saudi Basic Industries Corp
Priority date: 2013-05-06
Filing date: 2014-05-05
Publication date: 2016-03-03
Also published as: EP2994416A1; WO2014181243A1; CN105189343A; CN105189343B

Abstract

The present invention provides a method and apparatus for recovery of reformed gas produced in a methanol plant during startup. In one aspect, the method for recovery of a reformed gas produced in a methanol plant during startup comprising: a) decreasing the temperature of the methanol plant reformed gas comprising (1) water in an amount no greater than 2.5 wt %, based on the total weight of the reformed gas, (2) methane in an amount that ranges from 1 wt % to 8 wt %, based on the total weight of the reformed gas, (3) hydrogen, (4) nitrogen, (5) carbon dioxide, and (6) carbon monoxide, to remove at least some of the water from the reformed gas; and b) using the water removed reformed gas as fuel in a steam reformer.

Description

BACKGROUND

In existing methanol reforming processes, during normal plant startup more than 120,000 kg/hr of reformed gas is vented from the reformer through the flaring system. The vented gas decreases overall plant efficiency, and increases the environmental impact of plant operation, while wasting substantial amounts of energy.
Accordingly, a new process is needed, that recovers the reformed gas thus reducing venting of reformed gas which reduces waste, enhances plant productivity by using the reformed gas as a fuel during plant startup, while concurrently reducing the carbon footprint of plant operation.

SUMMARY

In accordance with the purpose(s) of the invention, as embodied and broadly described herein, the invention, satisfies these and other needs. In one aspect, a method for recovery of a reformed gas produced in a methanol plant during startup is provided. The method comprises decreasing the temperature of the methanol plant reactor reformed gas comprising (1) water in an amount no greater than 2.5 wt %, based on the total weight of the reformed gas, (2) methane in an amount that ranges from 1 wt % to 8 wt %, based on the total weight of the reformed gas, (3) hydrogen, (4) nitrogen, (5) carbon dioxide, and (6) carbon monoxide, to remove at least some of the water from the reformed gas; and using the water removed reformed gas as fuel in the methanol plant reactor.
In another aspect, an apparatus for recovery of a reformed gas, where the reformed gas is produced in a methanol plant during startup, is provided. The apparatus comprises (1) water in an amount no greater than 2.5 wt %, based on the total weight of the reformed gas, (2) methane in an amount that ranges from 1 wt % to 8 wt %, based on the total weight of the reformed gas, (3) hydrogen, (4) nitrogen, (5) carbon dioxide, and (6) carbon monoxide, where the reformed gas is produced in a methanol plant during startup comprising: a closed loop line from a reformed gas flare stack line to a fuel line for the steam reformer; wherein the closed loop line comprises a heat exchanger; and wherein the heat exchanger cools the reformed gas.
While aspects of the present invention can be described and claimed in a particular statutory class, such as the system statutory class, this is for convenience only and one of skill in the art will understand that each aspect of the present invention can be described and claimed in any statutory class. Unless otherwise expressly stated, it is in no way intended that any method or aspect set forth herein be construed as requiring that its steps be performed in a specific order. Accordingly, where a method claim does not specifically state in the claims or descriptions that the steps are to be limited to a specific order, it is no way intended that an order be inferred, in any respect. This holds for any possible non-express basis for interpretation, including matters of logic with respect to arrangement of steps or operational flow, plain meaning derived from grammatical organization or punctuation, or the number or type of aspects described in the specification.

BRIEF DESCRIPTION OF THE FIGURES

The accompanying figures, which are incorporated in and constitute a part of this specification, illustrate several aspects and together with the description serve to explain the principles of the invention.

FIG. 1 illustrates the conventional process.

FIG. 2 illustrates a version of the inventive process described herein.

Additional advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or can be learned by practice of the invention. The advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.

DESCRIPTION

The present invention can be understood more readily by reference to the following detailed description of the invention and the Example included therein.
Before the present articles, systems, devices, and/or methods are disclosed and described, it is to be understood that they are not limited to specific synthetic methods unless otherwise specified, or to particular reagents unless otherwise specified, as such may, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular aspects only and is not intended to be limiting. Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, examples of methods and materials are now described.

DEFINITIONS

As used in the specification and the appended claims, the singular forms “a,” “an” and “the” include plural referents unless the context clearly dictates otherwise.
Ranges can be expressed herein as from “about” one particular value, and/or to “about” another particular value. When such a range is expressed, a further aspect includes from the one particular value and/or to the other particular value. Similarly, when values are expressed as approximations, by use of the antecedent “about,” it will be understood that the particular value forms a further aspect. It will be further understood that the endpoints of each of the ranges are significant both in relation to the other endpoint, and independently of the other endpoint. It is also understood that there are a number of values disclosed herein, and that each value is also herein disclosed as “about” that particular value in addition to the value itself. For example, if the value “10” is disclosed, then “about 10” is also disclosed. It is also understood that each unit between two particular units are also disclosed. For example, if 10 and 15 are disclosed, then 11, 12, 13, and 14 are also disclosed.
References in the specification and concluding claims to parts by weight of a particular element or component in a composition denotes the weight relationship between the element or component and any other elements or components in the composition or article for which a part by weight is expressed. Thus, in a compound containing 2 parts by weight of component X and 5 parts by weight component Y, X and Y are present at a weight ratio of 2:5, and are present in such ratio regardless of whether additional components are contained in the compound.
A weight percent (wt. %) of a component, unless specifically stated to the contrary, is based on the total weight of the formulation or composition in which the component is included.
As used herein, the terms “optional” or “optionally” means that the subsequently described event or circumstance can or can not occur, and that the description includes instances where said event or circumstance occurs and instances where it does not.
Unless otherwise expressly stated, it is in no way intended that any method set forth herein be construed as requiring that its steps be performed in a specific order. Accordingly, where a method claim does not actually recite an order to be followed by its steps or it is not otherwise specifically stated in the claims or descriptions that the steps are to be limited to a specific order, it is no way intended that an order be inferred, in any respect. This holds for any possible non-express basis for interpretation, including: matters of logic with respect to arrangement of steps or operational flow; plain meaning derived from grammatical organization or punctuation; and the number or type of embodiments described in the specification.
Disclosed are the compositions themselves to be used within the methods disclosed herein. These and other materials are disclosed herein, and it is understood that when combinations, subsets, interactions, groups, etc. of these materials are disclosed that while specific reference of each various individual and collective combinations and permutation of these compounds can not be explicitly disclosed, each is specifically contemplated and described herein. Thus, if there are a variety of additional steps that can be performed it is understood that each of these additional steps can be performed with any specific embodiment or combination of embodiments of the methods of the invention.

Method for Recovery

In one aspect, the present disclosure is directed towards a method for recovery of a reformed gas produced in a methanol plant during startup comprising: a) decreasing the temperature of the methanol plant reactor reformed gas comprising (1) water in an amount no greater than 2.5 wt %, based on the total weight of the reformed gas, (2) methane in an amount that ranges from 1 wt % to 8 wt %, based on the total weight of the reformed gas, (3) hydrogen, (4) nitrogen, (5) carbon dioxide, and (6) carbon monoxide, to remove at least some of the water from the reformed gas; and then b) using the water removed reformed gas as fuel in the methanol plant.
In one aspect, the recovery of the reformed gas can be used to increase the production and reduce the venting to have a positive impact on environment. In another aspect, the recovery of the reformed gas can reduce the venting, reduce the waste, enhance the production, and/or reduce the carbon footprint.
Typically, the reformed gas is a mixture of purge gas and natural gas during standard methanol plant operation. During the typical startup, there is no purge gas available, and the natural gas can be used to start the reformer heating. In the present invention, the reformed gas is recovered, rather than vented, during the startup. In one aspect, the reformed gas is then used as fuel during the startup. In another aspect, additional natural gas can be added to the reformed gas, if the reformed gas is not sufficient or if the heating value is not adequate.
In a further aspect, the decreased temperature of the reformed gas ranges from 80° C. to 100° C., including exemplary values of 83° C., 85° C., 87° C., 90° C., 93° C., 95° C., and 97° C. In a further aspect, the temperature range can be derived from any two exemplary values. For example, the temperature of the reformed gas ranges from 83° C. to 97° C.
In one aspect, the temperature depends on the percentage of water in the reformed gas. In another aspect, the reformed gas temperature decreases to the point where the water can separate from the gas.
In one aspect, the time for startup ranges from 9 hours to 25 hours, including exemplary values of 10 hrs, 13 hrs, 15 hrs, 17 hrs, 20 hrs, and 23 hrs. In a further aspect, the time can be in a range derived from any two exemplary values. For example, the time for startup can range from 10 hrs to 25 hrs.
In one aspect, the reformed gas is cooled by passing through a heat exchanger. In another aspect, the cooling can be performed with any cooling media depending on the required lowest temperature. In a further aspect, the required lowest temperature depends on the temperature at which the water can be separated from the gas.
In another aspect, the reformed gas is dried by passing through a separator. In one aspect, the reformed gas is further dried by passing through a filter.
In one aspect, the reformed gas comprises water, methane, hydrogen, nitrogen, carbon dioxide, and carbon monoxide. In another aspect, the reformed gas consists of water, methane, hydrogen, nitrogen, carbon dioxide, and carbon monoxide. In a yet further aspect, the reformed gas consists of methane, hydrogen, nitrogen, carbon dioxide, and carbon monoxide.
In a further aspect, the reformed gas comprises hydrogen is present in an amount ranging from 50 wt % to 92.9 wt % hydrogen based on the total weight of the reformed gas; water is present in an amount ranging from 0 wt % to 2.5 wt % based on the total weight of the reformed gas; nitrogen is present in an amount ranging from 0.1 wt % to 5 wt % based on the total weight of the reformed gas; carbon monoxide is present in an amount ranging from 5 wt % to 20 wt % based on the total weight of the reformed gas; carbon dioxide is present in an amount ranging from 1 wt % to 15 wt % based on the total weight of the reformed gas; and methane is present in an amount ranging from 1 wt % to 8 wt % based on the total weight of the reformed gas.
In an even further aspect, the reformed gas comprises about 71.7 wt % hydrogen, about 2.5 wt % water, about 1.1 wt % nitrogen, about 14.3 wt % carbon monoxide, about 7.4 wt % carbon dioxide, and about 3 wt % methane.
In another aspect, the reformed gas comprises water in an amount no greater than 2.5 wt %, based on the total weight of the reformed gas. In a further aspect, the reformed gas comprises water in an amount ranging from 0 wt % to 2.5 wt %. In another aspect, the amount of water can be in a range derived from any two exemplary values. For example, the reformed gas comprises water in an amount ranging from 0 wt % to 2.0 wt %, or greater than 0 wt % to 2.0 wt %, or 0.3 wt % to 1.7 wt %.
In one aspect, between about 55% and about 99% of water in the reformed gas is removed. In a further aspect, the amount of water can be in a range derived from any two exemplary values. For example, between 60% and 99% (or between 70% and 99%) of water in the reformed gas is removed.
In one aspect, removing water from the reformed gas comprises decreasing the temperature of the reformed gas and drying the cooled reformed gas. In another aspect, the water is removed by using a heat exchanger, a separator, and/or a filter. In a further aspect, the water is a removed using any suitable method of absorption or adsorption.
In a further aspect, the water removed reformed gas is cycled to a point before entry of natural gas in the methanol plant.
In one aspect, the method further comprises adding natural gas to the reformed gas after removing water.
In another aspect, the natural gas is added to the reformed gas in an amount ranging from 399,300 kg/25 hours of natural gas is added per about 1,339,307 kg/25 hours of reformed gas during plant startup. In a further aspect, the natural gas added depends on the heating value required. The amount of natural gas added above has been calculated based on the heat typically required for a methanol plant.
In a further aspect, the total amount of natural gas saved by use of reformed gas as fuel is about 6132 MMNTU/25 hrs. In another aspect, the amount of natural gas saved is calculated based on the typical methanol plant.
In another aspect, the reformed gas comprises hydrogen in an amount ranging from 50 wt % to 92.9 wt %. For example, the reformed gas can comprise hydrogen in an amount ranging from 55 wt % to 85 wt %, or 61 wt % to 74 wt %.
In one aspect, the reformed gas comprises methane in an amount that ranges from 1 wt % to 8 wt %, based on the total weight of the reformed gas. In a further aspect, the amount of methane is present in a range derived from any two exemplary values. For example, the reformed gas comprises methane in an amount that ranges from 1 wt % to 7 wt %, or 1.5 wt % to 5 wt %. In another aspect, the reformed gas comprises methane in an amount of 3 wt %.
In another aspect, the reformed gas comprises nitrogen in an amount that ranges from 0.1 wt % to 5 wt %. In a further aspect, the range can be derived from any two exemplary values. For example, the reformed gas can comprise nitrogen in an amount that ranges from 2 wt % to 5 wt %.
In one aspect, the reformed gas comprises carbon dioxide in an amount that ranges from 1 wt % to 15 wt %. In further aspects can be in a range derived from any two exemplary values. For example, the reformed gas can comprise carbon dioxide in an amount that ranges from 6 wt % to 10 wt %.
In another aspect, the total impact of CO₂is 900 to 1200 MT/25 hr, e.g., 1098 MT/25 hr. In one aspect, the total impact of CO₂is calculated for the typical methanol plant. In another aspect, the total impact of CO₂can change depending on the plant capacity.
In a further aspect, the reformed gas comprises carbon monoxide in an amount that ranges from 5 wt % to 20 wt %. In further aspects can be in a range derived from any two exemplary values. For example, the reformed gas can comprise carbon monoxide in an amount that ranges from 6 wt % to 10 wt %.
In another aspect, the reformed gas heating value is 50,000 Kcal/Kg mol to 60,000 Kcal/Kg mol, e.g., 57,520 Kcal/Kg mol. In a further aspect, the reformed gas heating value is calculated for the typical methanol plant. In one aspect, the reformed gas heating value can vary from licensor to licensor.
In a further aspect, the natural gas heating value is 180,000 Kcal/Kg mol to 200,000 Kcal/Kg mol, e.g., 192,930 Kcal/Kg mol. In one aspect, the natural gas heating value is calculated for the typical methanol plant and can vary depending on the plant.
In one aspect, the flow of reformed gas ranges from 18448 kg/hr to 84596 kg/hr. In further aspect, the flow can be in a range derived from any two exemplary values. For example, the flow of reformed gas can range from 19000 kg/hr to 80000 kg/hr.
In another aspect, the duty for the heat exchanger ranges from 4.2×10⁶KJ/hr to 6.5×10⁶KJ/hr and the amount of water removed from the reformed gas ranges from 55% to 98%. In one aspect, the duty for the heat exchanger ranges from 4.2×10⁶KJ/hr to 6.5×10⁶KJ/hr. The duty can be in a range derived from any two exemplary values. For example, the duty for the heat exchanger ranges from 4.3×10⁶KJ/hr to 6.4×10⁶KJ/hr.
The methods disclosed herein can use the inventive apparatuses.

Apparatus for Recovery

In one aspect, the present invention is directed towards an apparatus for recovery of a reformed gas comprising (1) water in an amount no greater than 2.5 wt %, based on the total weight of the reformed gas, (2) methane in an amount that ranges from 1 wt % to 8 wt %, based on the total weight of the reformed gas, (3) hydrogen, (4) nitrogen, (5) carbon dioxide, and (6) carbon monoxide, where the reformed gas is produced in a methanol plant during startup comprising: a closed loop line from a reformed gas flare stack line to a fuel line for the steam reformer, wherein the closed loop line comprises a heat exchanger, wherein the heat exchanger cools the reformed gas.
In one aspect, the apparatus is part of a methanol plant. As used herein, a methanol plant is a plant where methanol is produced from a raw material such as natural gas.
In one aspect, the reformed gas comprises water, methane, hydrogen, nitrogen, carbon dioxide, and carbon monoxide. In another aspect, the reformed gas consists of water, methane, hydrogen, nitrogen, carbon dioxide, and carbon monoxide. In a further aspect, the reformed gas comprises hydrogen is present in an amount ranging from 50 wt % to 92.9 wt % hydrogen based on the total weight of the reformed gas; water is present in an amount ranging from 0 wt % to 2.5 wt % based on the total weight of the reformed gas; nitrogen is present in an amount ranging from 0.1 wt % to 5 wt % based on the total weight of the reformed gas; carbon monoxide is present in an amount ranging from 5 wt % to 20 wt % based on the total weight of the reformed gas; carbon dioxide is present in an amount ranging from 1 wt % to 15 wt % based on the total weight of the reformed gas; and methane is present in an amount ranging from 1 wt % to 8 wt % based on the total weight of the reformed gas. In a yet further aspect, the reformed gas consists of methane, hydrogen, nitrogen, carbon dioxide, and carbon monoxide. In an even further aspect, the reformed gas comprises about 71.7 wt % hydrogen, about 2.5 wt % water, about 1.1 wt % nitrogen, about 14.3 wt % carbon monoxide, about 7.4 wt % carbon dioxide, and about 3 wt % methane. In one aspect, the reformed gas composition has been calculated based on a typical methanol plant.
In another aspect, the reformed gas comprises water in an amount no greater than 2.5 wt %, based on the total weight of the reformed gas. In a further aspect, the reformed gas comprises water in an amount ranging from 0 wt % to 2.5 wt %, e.g., greater than 0 to 2.5 wt %. In another aspect, the amount of water can be in a range derived from any two exemplary values. For example, the reformed gas comprises water in an amount ranging from 0 wt % to 2.0 wt %, e.g., greater than 0 to 2.0 wt %, or 0.1 wt % to 1.8 wt %
In one aspect, the closed loop line cools and dries the reformed gas. In another aspect, the heat exchanger reformed gas is cooled and is dried in a filter.
In one aspect, the loop line further comprises a separator and a filter wherein the separator, or the filter, or the combination thereof, removes 55% to 99% of the water from the reformed gas.
In one aspect, between about 55% and about 99% of water in the reformed gas is removed. In a further aspect, the amount of water can be in a range derived from any two exemplary values. For example, between 60% and 90% of water in the reformed gas is removed.
In a further aspect, downstream of the heat exchanger, the apparatus further comprises a mixer, wherein the mixer adds natural gas to the reformed gas.
In another aspect, the natural gas is added to the reformed gas in an amount ranging from 399,300 kg/25 hours of natural gas is added per about 1,339,307 kg/25 hours of reformed gas during plant startup. In one aspect, the amount of natural gas added depends on the required heating value. The above amount of natural gas is based on the typical methanol plant.
Referring now to FIG. 1, an existing process for the primary reformer during start up of a methanol plant is illustrated. In normal operation, a reformed fuel gas 3 is a mixture of purge gas and natural gas from the natural gas line 1. Purge gas can come from a methanol separator 7 and from a vent scrubber 9. During normal operation, purge gas can flow to a steam reformer 3 and a hydrodesulphurization section 8. Natural gas can be added to the purge gas in order to provide the required heating value of the fuel gas for the reformer. During normal operation, the reformed gas can be fed from a drain separator 4 to a methanol superconverter 5 through a compressor and no reformed gas goes to a flare stack 6. However, during normal startup, no purge gas is available and natural gas can be used to start heating the reformer. During startup, large amounts of reformed gas can be vented through a flare stack 6. When the purge gas is available, at 75% plant load, then natural gas and a purge gas mixture can be used as reformer fuel. In the current process, the high amount of reformed gas vented through the flare stack can have a negative impact on sustainability and reduce plant efficiency.
Referring now to FIG. 2, an aspect of the new process is illustrated. In existing methanol reforming technology, during conventional plant start-up, venting of enormous quantities of reformed gas would occur through a drain separator 23 to a flare stack 25 without a closed line loop comprising a heat exchanger 29, a separator 30 and a coalescing filter 31. During startup, no purge gas is available for reformer/hydrodesulphurization section 27 and natural gas via natural gas line 20 is used to start reformer heating. The disclosed process can recover the reformed gas produced in a methanol plant during startup and can use the reformed gas as fuel for a steam reformer 22 or as fuel for a package boiler 32. Use of reformed gas during startup requires, in this aspect, addition of a closed line loop comprising heat exchanger 29, separator 30 and a coalescing filter 31, to the existing process loop. The closed line loop intersects the existing fuel loop before flare stack 25 and upstream of mixer 21.
During startup, the venting temperature of the reformed gas can be around 80° C. to 100° C. The reformed gas can contain at most 2.5 wt % water. Use of this gas as reformer fuel during startup can require reduction of temperature to remove water. Exchanger 29 can reduce the temperature of the gas while separator 30 and coalescing filter 31 can remove water. Then reformed gas can be fed to mixer 21 and steam reformer 22. The heating value of the reformed gas 23 can be low but can be supplemented with natural gas 20 if necessary. Accordingly, the process described above can utilize the reformed gas and has the following advantages: venting and waste are reduced while production and carbon footprint are enhanced.
The apparatus disclosed herein can use the inventive methods.

Aspects

The disclosed compositions and methods include at least the following aspects.
Aspect 1: A method for recovery of a reformed gas produced in a methanol plant during startup comprising: (a) decreasing the temperature of the methanol plant reformed gas comprising (1) water in an amount no greater than 2.5 wt %, based on the total weight of the reformed gas, (2) methane in an amount that ranges from 1 wt % to 8 wt %, based on the total weight of the reformed gas, (3) hydrogen, (4) nitrogen, (5) carbon dioxide, and (6) carbon monoxide, to remove at least some of the water from the reformed gas; and (b) using the water removed reformed gas as fuel in the a steam reformer.
Aspect 2: The method of Aspect 1, wherein the reformed gas comprises hydrogen is present in an amount ranging from 50 wt % to 92.9 wt % hydrogen based on the total weight of the reformed gas; water is present in an amount ranging from 0 wt % to 2.5 wt % based on the total weight of the reformed gas; nitrogen is present in an amount ranging from 0.1 wt % to 5 wt % based on the total weight of the reformed gas; carbon monoxide is present in an amount ranging from 5 wt % to 20 wt % based on the total weight of the reformed gas; carbon dioxide is present in an amount ranging from 1 wt % to 15 wt % based on the total weight of the reformed gas; and methane is present in an amount ranging from 1 wt % to 8 wt % based on the total weight of the reformed gas.
Aspect 3: The method any one of Aspects 1-2, wherein the decreased temperature of the reformed gas is about 80° C. to 100° C.
Aspect 4: The method any one of Aspects 1-3, wherein from about 55% to about 99% of the water in the reformed gas is removed.
Aspect 5: The method any one of Aspects 1-4, wherein removing water from the reformed gas comprises decreasing the temperature of the reformed gas to cool the reformed gas and drying the cooled reformed gas.
Aspect 6: The method any one of Aspects 1-5, wherein the reformed gas is cooled by passing through a heat exchanger.
Aspect 7: The method any one of Aspects 1-6, wherein the reformed gas is dried by passing through a separator.
Aspect 8: The method any one of Aspects 1-7, wherein the reformed gas is further dried by passing through a filter.
Aspect 9: The method any one of Aspects 1-8, wherein the duty for the heat exchanger ranges from 4.2×10⁶KJ/hr to 6.5×10⁶KJ/hr and the amount of water removed from the reformed gas ranges from 55% to 99%.
Aspect 10: The method any one of Aspects 1-9, wherein the water removed reformed gas is recycled to a point before entry of natural gas in the methanol plant.
Aspect 11: The method any one of Aspects 1-10, further comprising adding natural gas to the reformed gas after removing water.
Aspect 12: The method any one of Aspects 1-11, wherein about 399,300 kg/25 hours of natural gas is added per about 1,339,307 kg/25 hours of reformed gas during plant startup.
Aspect 13: The method any one of Aspects 1-12, wherein the total amount of natural gas saved by use of reformed gas as fuel is about 6132 MMNTU/25 hrs.
Aspect 14: The method any one of Aspects 1-13 wherein flow of reformed gas is between about 18448 kg/hr and about 84596 kg/hr.
Aspect 15: An apparatus for recovery of a reformed gas comprising (1) water in an amount no greater than 2.5 wt %, based on the total weight of the reformed gas, (2) methane in an amount that ranges from 1 wt % to 8 wt %, based on the total weight of the reformed gas, (3) hydrogen, (4) nitrogen, (5) carbon dioxide, and (6) carbon monoxide, where the reformed gas is produced in a methanol plant during startup comprising: a closed loop line from a reformed gas flare stack line to a fuel line for a steam reformer; wherein the closed loop line comprises a heat exchanger; and wherein the heat exchanger cools the reformed gas.
Aspect 16: The apparatus of Aspect 15, wherein the closed loop line cools and dries the reformed gas.
Aspect 17: The apparatus any one of Aspects 15-16, wherein the loop line further comprises a separator and a filter wherein the separator, or the filter, or the combination thereof, removes from 55% to 99% of the water from the reformed gas.
Aspect 18: The apparatus according to Aspects 15-17, wherein downstream of the heat exchanger, the apparatus further comprises a mixer, wherein the mixer adds natural gas to the reformed gas.

EXPERIMENTAL

The following example is put forth so as to provide those of ordinary skill in the art with a complete disclosure and description of how the articles, devices and/or methods claimed herein are made and evaluated, and are intended to be purely exemplary of the invention and are not intended to limit the scope of what the inventors regard as their invention. Efforts have been made to ensure accuracy with respect to numbers (e.g., amounts, temperature, etc.), but some errors and deviations should be accounted for.

Example 1

The process is evaluated by use of plant data. Tables 1, 2 and 3 summarize the results.

TABLE 1

Reformed Gas Composition

		Reformed Gas
	Composition	VENT

	Hydrogen	71.69
	Water	2.49
	Nitrogen	1.13
	Carbon	14.31
	Monoxide
	Carbon Dioxide	7.36
	Methane	3.03

Total reformed gas required: Reformed gas: Heating Value is 57520 Kcal/Kgmol; Natural gas: Heating Value is 192930 Kcal/Kgmol

TABLE 2

Results

	Natural Gas to		Total Reformed
Time	Reformer	Units	Gas Required	Units

9 hrs	49500	Kg/9 hr	166029.8157	Kg/9 hr
4 hrs	47142.85714	Kg/4 hr	158123.634	Kg/4 hr
12 hrs	302657.1429	Kg/12 hr	1015153.73	Kg/12 hr
25 hrs	399300	Kg/25 hrs	1339307.18	Kg/25 hrs

Removal of 2.3% water requires a heat exchanger, a separator and a filter. The duties for the heat exchanger are as follows in Table 3:

TABLE 3

Results

Duty	Units	Comments

4.2 × 10⁶	KJ/hr	55% water removed
5.2 × 10⁶	KJ/hr	77% water removed
6.0 × 10⁶	KJ/hr	90% water removed
6.5 × 10⁶	KJ/hr	99% water removed

Aspen Hysys-7.2, a chemical engineering tool is used for the calculations. As per the calculations the total natural gas saving is equivalent to 6132 MMBTU/25 hrs. Total reformed gas used in startup is 1339307 kg/25 hrs. Minimum and maximum flow of reformed gas is 18448 kg/hr and 84596 kg/hr respectively during startup. Total impact of CO₂is 1098 MT/25 hr. Hydraulic calculations provide the size of the pipe. It is calculated that a 14″ pipe with 40 schedule is appropriate to handle this flow rate.
It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims.

Claims

1. A method for recovery of a reformed gas produced in a methanol plant during startup comprising:

a) decreasing the temperature of the methanol plant reformed gas comprising (1) water in an amount no greater than 2.5 wt %, based on the total weight of the reformed gas, (2) methane in an amount that ranges from 1 wt % to 8 wt %, based on the total weight of the reformed gas, (3) hydrogen, (4) nitrogen, (5) carbon dioxide, and (6) carbon monoxide, to remove at least some of the water from the reformed gas; and

b) using the water removed reformed gas as fuel in a steam reformer.

2. The method of claim 1, wherein the reformed gas comprises hydrogen is present in an amount ranging from 50 wt % to 92.9 wt % hydrogen based on the total weight of the reformed gas; water is present in an amount ranging from 0 wt % to 2.5 wt % based on the total weight of the reformed gas; nitrogen is present in an amount ranging from 0.1 wt % to 5 wt % based on the total weight of the reformed gas; carbon monoxide is present in an amount ranging from 5 wt % to 20 wt % based on the total weight of the reformed gas; carbon dioxide is present in an amount ranging from 1 wt % to 15 wt % based on the total weight of the reformed gas; and methane is present in an amount ranging from 1 wt % to 8 wt % based on the total weight of the reformed gas.

3. The method of claim 1, wherein the decreased temperature of the reformed gas is about 80° C. to 100° C.

4. The method of claim 1 wherein from about 55% to about 99% of the water in the reformed gas is removed.

5. The method of claim 1, wherein removing water from the reformed gas comprises decreasing the temperature of the reformed gas to cool the reformed gas and drying the cooled reformed gas.

6. The method of claim 1, wherein the reformed gas is cooled by passing through a heat exchanger.

7. The method of claim 1, wherein the reformed gas is dried by passing through a separator.

8. The method of claim 1, wherein the reformed gas is further dried by passing through a filter.

9. The method of claim 18, wherein the duty for the heat exchanger ranges from 4.2×10⁶KJ/hr to 6.5×10⁶KJ/hr and the amount of water removed from the reformed gas ranges from 55% to 99%.

10. The method of claim 1, wherein the water removed reformed gas is recycled to a point before entry of natural gas in the methanol plant.

11. The method of claim 1, further comprising adding natural gas to the reformed gas after removing water.

12. The method of claim 1, wherein about 399,300 kg/25 hours of natural gas is added per about 1,339,307 kg/25 hours of reformed gas during plant startup.

13. The method of claim 1, wherein the total amount of natural gas saved by use of reformed gas as fuel is about 6132 MMNTU/25 hrs.

14. The method of claim 1, wherein

flow of reformed gas ranges from 18448 kg/hr to 84596 kg/hr.

15. An apparatus for recovery of a reformed gas comprising (1) water in an amount no greater than 2.5 wt %, based on the total weight of the reformed gas, (2) methane in an amount that ranges from 1 wt % to 8 wt %, based on the total weight of the reformed gas, (3) hydrogen, (4) nitrogen, (5) carbon dioxide, and (6) carbon monoxide, where the reformed gas is produced in a methanol plant during startup comprising:

a closed loop line from a reformed gas flare stack line to a fuel line for a steam reformer;

wherein the closed loop line comprises a heat exchanger; and

wherein the heat exchanger cools the reformed gas.

16. The apparatus of claim 15, wherein the closed loop line cools and dries the reformed gas.

17. The apparatus of claim 15, wherein the loop line further comprises a separator and a filter wherein the separator, or the filter, or the combination thereof, removes from 55% to 99% of the water from the reformed gas.

18. The apparatus of claim 15, wherein downstream of the heat exchanger, the apparatus further comprises a mixer, wherein the mixer adds natural gas to the reformed gas.

19. A method for recovery of a reformed gas produced in a methanol plant during startup comprising:

a) decreasing the temperature of the methanol plant reformed gas comprising (1) water in an amount no greater than 2.5 wt %, based on the total weight of the reformed gas, (2) methane in an amount that ranges from 1 wt % to 8 wt %, based on the total weight of the reformed gas, (3) hydrogen, (4) nitrogen, (5) carbon dioxide, and (6) carbon monoxide, to a temperature of about 80° C. to 100° C. to remove at least some of the water from the reformed gas; and

b) using the water removed reformed gas as fuel in a steam reformer;

wherein the reformed gas comprises hydrogen is present in an amount ranging from 50 wt % to 92.9 wt % hydrogen based on the total weight of the reformed gas; water is present in an amount ranging from 0 wt % to 2.5 wt % based on the total weight of the reformed gas; nitrogen is present in an amount ranging from 0.1 wt % to 5 wt % based on the total weight of the reformed gas; carbon monoxide is present in an amount ranging from 5 wt % to 20 wt % based on the total weight of the reformed gas; carbon dioxide is present in an amount ranging from 1 wt % to 15 wt % based on the total weight of the reformed gas; and methane is present in an amount ranging from 1 wt % to 8 wt % based on the total weight of the reformed gas.